Letters to the editor

Altered Auditory Feedback Research Conditions and Situations of Everyday Life: Comments on Ingham, Moglia, Frank, Costello Ingham, and Cordes (1997)

We have read with interest the time-series design study by Ingham, Moglia, Frank, Costello Ingham, and Cordes (1997) which examines the effects of frequency-altered feedback (FAF) on the speech of four adults who stutter. Although their interpretation of their data suggested that the effects of FAF were not consistent across each of their participants as a function of each experimental condition, they recognized that the response of one participant (E.O.) reflected positively on the possible effectiveness of FAF in the clinical environment. They concluded: “If the reductions observed in E.O.’s stuttering also occur during conversational speech, it is possible that FAF may be clinically effective in controlling stuttering for others who stutter” (p. 369). However, the authors further caution that “the extent to which E.O.’s response to FAF represents the clinical population of adults who stutter is unknown, so the clinical significance of this finding for other people who stutter is uncertain” (p. 370). It must be recognized, however, that although participant E.O. may not be representative of the stuttering population, the same notion must be held out for any of the other participants who, according to the Ingham et al. interpretation, did not respond in a positive manner to the experimental conditions.

More importantly, Ingham et al. (1997) state that “outcomes ranged from no observable effect on stuttering (E.S.) to inconsistent effects (A.G. and F.G.) to consistent, sustained, substantial reductions in stuttering (E.O.)” (p. 369). We strongly suggest that the readership re-examine the data and figures presented by Ingham et al., especially the data for participants F.G. and A.G. Participant A.G. shows a robust effect, whereas participant F.G. “bottoms out” but clearly shows a positive effect in the FAF conditions. Therefore, we interpret the data from these participants as showing a substantial experimental effect to FAF. In our opinion Ingham and colleagues simply misrepresent their own data.

Although we concur with the notions of Ingham et al. (1997) that certain caution must be taken in overgeneralizing such data to the population of people who stutter, the findings reported in the literature from our laboratories and by Dr. Howell’s group (Howell, El-Yaniv, & Powell, 1987, 1990) must not be ignored. As researchers, we have examined the effect of altered auditory feedback (AAF, i.e., FAF, delayed auditory feedback, masked auditory feedback) in controlled experimental environments. What have we found? Simply put: AAF is a powerful fluency enhancer for people who stutter at normal and fast speech rates when reading text in an experimental setting, in front of varying audience sizes, and when talking to strangers on the telephone (see Armson, Kalinowski, Foote, Witt, & Stuart,1997; Hargrave, Kalinowski, Stuart, Armson, & Jones, 1994; Howell,1990; Howell, 1990; Howell, El-Yaniv, & Powell, 1987; Kalinowski, Armson, Roland-Mieszkowski, Stuart, & Gracco, 1993; Kalinowski, Stuart, Sark, & Armson, 1996; MacLeod, Kalinowski, Stuart, & Armson, 1995; Stuart, Kalinowski, Armson, Stenstrom, & Jones,1996; Stuart, Kalinowski, & Rastatter, 1997; Stuart, Miller, Kalinowski, & Rastatter,1997; Zimmerman, Kalinowski, Stuart, & Rastatter, 1997). We will agree, however, that the notion of “ecological validity” in such experimentation is subject to debate (see Ingham,1997 and Kalinowski, Stuart, & Armson, 1997). That is, measuring stuttering occurrences in spontaneous speech versus reading text in a sound-treated suite may not be representative of behavior occurring within the “natural” communisphere of individuals who stutter. Additionally, issues of adaptation to AAF and permutation of these parameters should be examined. We think these are all questions of interest and must be dealt with empirically before dismissing the clinical applications of AAF.

Like all phenomena, AAF needs to be examined in a number of contexts with research paradigms designed to look beyond the experimental and clinical settings. We are in agreement with Ingham et al. (1997) that further research must be undertaken in this exciting area of fluency enhancement. Like Ingham et al. (1997) we feel “It is clear…that these findings justify further research on the use of this procedure with groups of stuttering adults to ascertain the scope, extent, and duration of its effects” (p. 370). We suggest, in addition, that scope, extent, and duration of traditional motoric targets on fluency be examined in a similar diligent manner. In other words, we ask why the “gold standard” of testing in ecologically sensitive contexts currently being demanded of AAF has not been required of the plethora of motoric strategies currently in use. For example, one must wonder why there has been no examination of whether motoric strategies adapt. That is, do the fluency-enhancing effects of “gentle onset,” “continuous phonation,” and “rate control” habituate or wear off?

We would like to point out to the readership that we have consistently maintained that an AAF prosthetic device should be used in conjunction with motoric strategies or alterations (e.g., gentle onsets and continuous phonation) that serve to supplement the clinical effectiveness of AAF (Armson et al., 1997; Hargrave et al., 1994; Kalinowski et al., 1996; MacLeod et al., 1995; Stuart et al., 1997; Zimmerman et al., 1997). It is not our belief that a prosthetic device should be used alone for fluency enhancement either in or outside of the clinical environment. Therefore, experiments that look at the fluency-enhancing effects of AAF without other fluencyenhancing strategies (i.e., motoric strategies) cannot serve as the definitive word on clinical or therapeutic uses of AAF. Finally, it should be noted that we strongly disagree with Ingham et al.’s (1997) dismissal of the clinical and theoretical importance of AAF in regard to stuttering and speech motor control in general. We do support, however, their notion that much further research in the area of AAF needs to be done.

Joseph Kalinowski Michael P. Rastatter Andrew Stuart Department of Communication Sciences and Disorders East Carolina University Greenville, NC


Armson, J., Kalinowski, J., Foote, S., Witt, C., & Stuart, A. (1997). Effect of frequency altered feedback on stuttering under various audience conditions. European Journal of Disorders of Communication, 32, 359-366.

Hargrave, S., Kalinowski, J., Stuart, A., Armson, J., & Jones, K. (1994). Stuttering reduction under frequencyaltered feedback at two speech rates. Journal of Speech and Hearing Research, 37, 1313-1320. Howell, P. (1990). Changes in voice level caused by several forms of altered feedback in fluent speakers and stutters. Language and Speech, 33, 325-338.

Howell, P., El-Yaniv, N., & Powell, D. J. (1987). Factors affecting fluency in stutterers. In H. F. M. Peters & W. Hulstijin (Eds.), Speech motor dynamics in stuttering (pp. 361-369). New York: Springer-Verlag.

Ingham, R. J. (1997). On some valid distinctions between findings from single-subjects and group studies of stuttering: Some reflections on Kalinowski et al. (1995). Journal of Fluency Disorder, 22, 51-56. Ingham, IL J., Moglia, R. A., Frank, P., Costello Ingham, J., & Cordes, A. (1997). Experimental investigation of the effects of frequency-altered feedback on the speech of adults who stutter. Journal of Speech, Language, and Hearing Research, 40, 361-372.

Kalinowski, J., Armson, J., Roland-Mieszkowski, M., Stuart, A., & Gracco, V. L. (1993). Effects of alterations in auditory feedback and speech rate on stuttering frequency. Language and Speech, 36, 1-16.

Kalinowski, J., Stuart, A., &Armson, J. (1997). Response to Ingham: Seeking the truthfulness of stuttering research data. Journal of Fluency Disorders, 22, 57-59. Kalinowski, J., Stuart, A., Sark, S., &Armson, J. (1996). Stuttering amelioration at various auditory feedback delays and speech rates. European Journal of Disorders of Communication, 31, 259-269.

Stuart, A., Kalinowski, J., Armson, J., Stenstrom, R., & Jones, K. (1996). Stuttering reduction under frequencyaltered feedback of plus and minus one-half and onequarter octaves at two speech rates. Journal of Speech and Hearing Research, 39, 396-401.

Stuart, A., Kalinowski, J., & Rastatter, M. P. (1997). Effects of monaural and binaural altered auditory feedback on stuttering frequency. Journal of the Acoustical Society of America, 101, 3806-3809.

Stuart, A., Miller, R. K., Kalinowski, J., & Rastatter, M. P. (1997). The effect of speaking into a passive resonator on stuttering frequency. Perceptual and Motor Skills, 84, 1343-1346.

Zimmerman, S., Kalinowski, J., Stuart, A., & Rastatter, M. P. (1997). Effect of altered auditory feedback on people who stutter during scripted telephone conversations. Journal of Speech, Language, and Hearing Research, 30, 1130-1135.

Received August 6, 1997 Accepted December 9, 1997

The Effects of Frequency-Altered Feedback on Stuttering: Reply to Kalinowski, Rastatter, and Stuart (1998)

Kalinowski, Rastatter, and Stuart (1998) comment on the interpretation and significance of four singlesubject design investigations of frequency-altered feedback (FAF) that were published in Ingham, Moglia, Frank, Ingham, and Cordes (1997). We respond to the specific criticism that we misinterpreted our data and then to some of the larger issues raised by Kalinowski et al.

Ingham et al. (1997): Subjects A.G. and F.G.

Ingham et al. arranged for four adults who stuttered to complete oral reading tasks and spontaneous speaking tasks during normal auditory feedback (NAF) and two FAF (+1 or -1 octave) conditions. Within each experiment, the subject spoke for a minimum of 12 min in each phase. If there was evidence of a response to FAF, the subject then continued to speak for a minimum of 45 min with FAF. Our study’s addition of spontaneous speech tasks and our use of at least 45 min of speech to evaluate a positive response to FAF were modest steps toward a more clinically significant evaluation of FAF than had been previously available. (Earlier studies had used only oral reading tasks and had used samples of not more than 2 min of speech in each condition.) It seemed to us especially critical to evaluate whether speakers would respond differently to relatively long periods of FAF than they do to relatively short periods of exposure because of the known changes that occur during extended periods of auditory masking (another altered-audition condition).

We reported that our results “showed no consistencies across subjects in responses to FAF: One subject showed no response, another produced an initial temporary response, a third showed a deterioration in speech quality with minimal reductions in stuttering, and a fourth displayed substantial and sustained improvements in speech performance” (1997, p. 361). Kalinowski et al. (1998) assert, however, that the second and third of these subjects, A.G. and EG., “show[ed] a substantial experimental effect to FAF” and that our claim that they did not respond positively to FAF was therefore a misrepresentation of our data. Remarkably, Kalinowski et al. make this serious claim without offering any explanation or databased detail; they merely suggest that this will be apparent if readers examine our data. We have done just that, as have many others, and we find absolutely no reason to alter our interpretation of the findings.

The validity of experimental effects within a singlesubject or time-series experiment requires that clear and unambiguous data trends be related to experimental phase changes, and that these trends be replicated within subjects (Barlow & Hersen, 1984). Subject A.G. showed an initial positive response to FAF, but in the second part of his experiment, as we correctly reported, this initial positive effect was not sustained: “In fact, the frequency of stuttered intervals per trial reached levels that overlapped those found during the NAF conditions” (Ingham et al., 1997, p. 367). Figure 4 (p. 368) clearly shows that during an initial FAF 3-min trial A.G. produced zero 5-s stuttered intervals (out of a possible 36), but he eventually displayed 9-15 stuttered intervals per trial, well within the 9-25 range of stuttered intervals that he produced during NAF conditions (60% of A.G.’s -1 FAF trials contained numbers of stuttered intervals that were within the range obtained under NAF).

Subject F.G. did appear to reduce his stuttering somewhat in oral reading during FAF, but this was accompanied by a dramatic deterioration in his speech naturalness ratings: “During the FAF conditions F.G. was perceived to lose articulatory control, demonstrating dysarthric-like behavior and becoming almost unintelligible. This effect was replicated across the two FAF phases” (Ingham et al., 1997, p. 366). A similar deterioration in speech naturalness occurred during his spontaneous speech experiment. These results were obtained, as we also reported, in the context of a relatively small and inconsistent reduction in stuttered intervals for FAF conditions as compared with NAF conditions.

In short, the data from these two subjects did not suggest sustained reductions in stuttering, much less suggest large sustained reductions in stuttering with satisfactory speech naturalness that could be tied to the experimental conditions. We see absolutely nothing to justify the claim that we have misrepresented our data, and we encourage readers to trace the results in the original figures for themselves.

Larger Issues

Kalinowski et al. also ask why demands for more ecologically valid studies of altered auditory feedback (AAF) procedures have not also been applied to “the plethora of motoric strategies” that are currently in use. This comment seems irrelevant as a criticism of the Ingham et al. (1997) study, unless every study is to be criticized for studying only what it studied instead of studying something else. It is also a questionable interpretation of the stuttering research literature, because many treatment studies have investigated prolonged speech and its variants and shown sustained changes in multiple real-life speaking situations (e.g., Boberg & Kully, 1994; Howie, Tanner, & Andrews, 1981; Onslow, Costa, Andrews, Harrison, & Packman, 1996). Several investigators have also attempted to operationalize some of the components of prolonged speech, including the duration of phonation or voice time in the speech of adults who stutter (Gow & Ingham, 1992; Hillis, 1993; Ingham, Montgomery, & Ulliana,1983), using extensive periods of speaking and finding no evidence of the waning effects that Kalinowski et al. refer to as “the common phenomena of adaptation.” In short, “the `gold standard’ of testing in ecologically sensitive contexts” has not only been “currently…demanded of AAF,” it has been, and should be, applied to any procedure that is claimed to reduce stuttering. It is also true, and in this sense we agree with Kalinowski et al., that the specific speech pattern changes that are necessary to produce prolonged speech have not been satisfactorily described or isolated in a way that has allowed them to be completely or systematically investigated. We certainly agree with Kalinowski et al.’s suggestion that there is a need for far more research on the parameters that have been regarded as derivatives of prolonged speech.

Finally, we would like to comment on Kalinowski et al.’s claim that they have “consistently maintained that an AAF prosthetic device should be used in conjunction with motoric strategies or alterations (e.g., gentle onsets and continuous phonation) that serve to supplement the clinical effectivness of AAF.” We have read carefully each of the publications listed by Kalinowski et al., and we find no evidence that Kalinowski and colleagues have ever investigated the effects of using FAF (or any other AAF procedure) in conjunction with additional motoric strategies. In fact, most recently, Zimmerman, Kalinowski, Stuart, and Rastatter (1997, p. 1131) instructed subjects specifically to “refrain from the use of fluency-enhancing strategies they may have been taught or devised on their own.” If additional speech-pattern changes are necessary for FAF to be effective in a clinical context, then we are mystified by Kalinowski and colleagues’ failure to provide experimental evidence to demonstrate this point. Clearly, if the conclusion that Kalinowski and his colleagues have reached is that AAF should be used “in conjunction with motoric strategies” that are, themselves, known to reduce stuttering, then these investigators will need to provide adequately controlled comparisons demonstrating that the addition of AAF makes some demonstrable difference or produces speech that is different from the speech obtained with AAF alone and with speech pattern changes alone.

We believe that once a procedure, such as FAF, has been demonstrated to produce variable effects, then the most profitable avenue for science to follow is to try to locate the source of that variance. If the effects of FAF are not lasting, or if FAF produces unnatural changes in speech, then it is important to understand and gain control over the variables responsible for those changes: Are variable changes occurring because of uncontrolled alterations in speech motor behavior (presumably partially induced by auditory stimulation), because of neural changes, or because of changes in a host of other variables known to influence stuttering? To some extent, this is similar to the path that emerged out of the DAF investigations with stuttering during the 1970s-a path that led, ironically, to the realization that DAF was probably a redundant component within the DAF-effect on stuttering (Bloodstein, 1995; Ingham, 1984). Repeatedly comparing groups of persons who do and who do not stutter for the effects of AAF procedures not only fails to recognize what has been learned from past research on stuttering, but follows the same clinically barren path that has been trodden by, for example, a huge amount of speechmotor research on stuttering (Ingham, in press; Young, 1994). We agree that there may well be a lot to be learned from the effects of FAF on stuttering, but there may also be a lot to learn from the signs of its ineffectiveness.

Roger J. Ingham Janis C. Ingham University of California, Santa Barbara Anne K. Cordes University of Georgia Athens Richard Moglia Peter Frank* University of California, Santa Barbara

*The authorship sequence reflects a posthumous acknowledgment to our friend and colleague, Peter Frank, who was also coauthor on the Ingham et al. ( 1997) paper. He died in June 1996.


Barlow, D. H., & Herson, M. (1984). Single case experimental designs: Strategies for studying behavior change (2nd ed.). New York: Pergamon.

Bloodstein, O. (1995). A handbook on stuttering (5th ed.). San Diego, CA: Singular Publishing Group.

Boberg, E., & Kully, D. (1994). Long-term results of an intensive treatment program for adults and adolescents who stutter. Journal of Speech and Hearing Research, 37, 1050-1059.

Gow, M. L., & Ingham, R. J. (1992). Modifying electroglottograph-identified intervals of phonation: The effect on stuttering. Journal of Speech and Hearing Research, 35, 495-511.

Hillis, J. W. (1993). Ongoing assessment in the management of stuttering: A clinical perspective. American Journal of Speech-Language Pathology, 2, 24-37.

Howie, P. M., Tanner, S., &Andrews, G. (1981). Shortand long-term treatment program for adult stutterers. Journal of Speech and Hearing Disorders, 46, 104-109.

Ingham, R. J. (1984). Stuttering and behavior therapy: Current status and experimental foundations. San Diego, CA: College-Hill Press.

Ingham, R. J. (in press). On learning from speech-motor control research on stuttering. In A. K. Cordes & R. J. Ingham (Eds.), Toward treatment efficacy for stuttering: A search for empirical bases. San Diego: Singular Publishing Group.

Ingham, R. J., Moglia, R. Ao, Frank, P., Ingham, J. C., & Cordes, A. K (1997). Experimental investigation of the effects of frequency-altered auditory feedback on the speech of adults who stutter. Journal of Speech, Language, and Hearing Research, 40, 349-360.

Ingham, R. J., Montgomery, J., & Ulliana, L. (1983). An investigation on the effect of manipulating phonation duration on stuttering. Journal of Speech and Hearing Research, 26, 579-587.

Kalinowski, J., Rastatter, M. P., & Stuart, A. (1998). Altered auditory feedback research conditions and situations of everyday life: Comments on Ingham et al. ( 1997). Journal of Speech, Language, and Hearing Research, 41, 511-513.

Onslow, M., Costa, L.,Andrews, C., Harrison, E., & Packman, A. (1996). Speech outcomes of a prolongedspeech treatment for stuttering. Journal of Speech and Hearing Research, 39, 734-749.

Young, M. A. (1994). Evaluating differences between stuttering and nonstuttering speakers: The group difference design. Journal of Speech and Hearing Research, 37, 522-534.

Zimmerman, S., Kalinowski, J., Stuart,Aa, & Rastatter, M. P. (1997). Effect of altered auditory feedback on people who stutter during scripted telephone conversations. Journal of Speech, Language, and Hearing Research, 40, 1130-1134.

Received October 10,1997

Accepted December 9, 1997

Copyright American Speech-Language-Hearing Association Jun 1998

Provided by ProQuest Information and Learning Company. All rights Reserved