Electronic fluency device

Electronic fluency devices (also known as assistive devices, electronic aids, altered auditory feedback devices and altered feedback devices) are electronic devices intended to improve the fluency of persons who stutter. Most electronic fluency devices change the sound of the user's voice in his or her ear.

Electronic fluency device

Types

Electronic fluency devices can be divided into two basic categories.

Computerized feedback devices

Computerized feedback devices (such as CAFET or Dr. Fluency) use computer technology to increase control over breathing and phonation. A microphone gathers information about the stutterer’s speech and feedback is delivered on a computer screen. Measurements include intensity (loudness), voice quality, breathing patterns, and voicing strategies.[1] These programs are designed to train features related to prolonged speech, a treatment technique which is frequently used in stuttering therapy. No peer-reviewed studies have been published showing the effectiveness of commercial systems in a clinical context.[3] A study of electromyographic (EMG) feedback in children and adolescents found it to be as effective as other treatments (home-based and clinic-based smooth speech training) in the short and longterm.[4][5]

Altered auditory feedback devices

Altered auditory feedback (AAF) such as singing, choral speaking, masking, delayed or frequency altered feedback have long been known to reduce stuttering.[6][7] Early altered auditory feedback devices were large and thus confined to the laboratory or therapy room, but advances in electronics have permitted increasingly portable devices such as Derazne Correctophone, the Edinburgh Masker, the Vocaltech Clinical Vocal Feedback Device, the Fluency Master and the SpeechEasy.[8] Current devices may be similar in size and appearance to a hearing aid, including in-the-ear and completely-in-the-canal models.[2][9]

Masking

White noise masking has been well documented to reduce stuttering.[2][10][11] Clinic-based and portable devices, such as the Edinburgh Masker (since discontinued) have been developed to deliver masking, and found that masking was effective in reducing stuttering,[12][13] though many found that reduction in stuttering faded with time.[14] Interest in masking reduced during the 1980s as a result of studies finding delayed auditory feedback and frequency altered feedback were more effective in reducing stuttering.[2][10]

Delayed auditory feedback

The effect of delayed auditory feedback (DAF) in reducing stuttering has been noted since the 1950s.[15][16] A DAF user hears his or her voice in headphones, delayed a fraction of a second. Typical delays are in the 50 millisecond to 200 millisecond range.[2] In stutterers, DAF may produce slow, prolonged but fluent speech. In the 1960s to 1980s, DAF was mainly used to train prolongation and fluency. As the stutterer masters fluent speech skills at a slow speaking rate, the delay is reduced in stages, gradually increasing speaking rate, until the person can speak fluently at a normal speaking rate.[17][18] It was not until the 1990s that research began to focus on DAF in isolation. Recent studies have moved from longer delays to shorter delays in the 50 millisecond to 75 millisecond range, and have found that speakers can maintain fast rates and achieve increased fluency at these delays.[2][10][19][20] Delayed auditory feedback presented binaurally (i.e. in both ears) is more effective than that presented in monaurally, or in one ear only.[21]

Frequency-altered feedback

Pitch-shifting frequency-altered auditory feedback (FAF) changes the pitch at which the user hears his or her voice. Varying pitch from quarter, half or full octave shift typically results in 55–74% decreases stuttering in short reading tasks.[10][20][22][23] Individuals differ as to direction and extent of the pitch shift required to maximally reduce stuttering.[24] In studies that gave longer exposure to FAF and used more meaningful daily life tasks such as generating a monologue, only some participants experienced a reduction in stuttering.[25][26] Initial claims that AAF was more powerful than FAF in reducing stuttering have not been supported by subsequent research.[2] FAF is, like DAF, more effective when presented binaurally.[21] In the last years a number of smart phone apps have been developed that implement DAF/FAF as software and are much cheaper than the special hardware devices, see External links.

Effectiveness

Studies have shown that altered auditory feedback (including delayed auditory feedback, frequency altered feedback) as provided by devices such as the Casa Futura School DAF machine or SpeechEasy can immediately reduce stuttering by 40 to 80 per cent in reading tasks.[2][27][28] Laboratory studies suggest that reductions in stuttering with an electronic fluency device can occur without a reduced speech rate, and that speech naturalness is often enhanced with AAF.[9][25] However, the effects of altered feedback are highly individualistic, with some obtaining considerable increases in fluency, while others receive little or no benefit.[2][25][29]

A 2006 review of stuttering treatments noted that none of the treatment studies on altered auditory feedback met the criteria for experimental quality.[30] In addition, studies have been critiqued for failing to demonstrate ecological validity; in particular that AAF effects continue over the long term and in everyday speaking situations.[8][18][31] The high-profile promotion in the media of devices such as the "SpeechEasy" has been criticized as inappropriate given the lack of scientific evidence for their effectiveness.[18][31][32]

There are few published studies on the effect of the AAF in the daily activities of life; studies have mainly examined the effect of AAF on short oral reading tasks, with some studying the giving of a monologue that is usually short in duration.[2] Several studies have produced group results that stutterers using the SpeechEasy show greater reductions in reading than for monologue and conversation.[8][29][33] Using AAF was effective in reducing stuttering in scripted telephone calls and giving presentations according to two studies.[20][22] Another study examining the effects of the SpeechEasy in more naturalistic situations (conversation and asking questions of strangers outside the clinic) found that the SpeechEasy failed to show a significant effect following 6 months of use, though individual subjects varied in their response.[8] A further study examining the use of the device during phone and face to face conversation also found wide variations in stuttering reduction, with just under half exhibiting stable improvement over the course of the 4 months of the study.[33]

While there is evidence of the immediate, short-term effectiveness of AAF devices in reducing stuttering,[8][29] the longterm effects of altered feedback are unclear. There is some limited experimental data that in some speakers the effect of AAF may fade after a few minutes of exposure,[26] and some anecdotal reports suggest that over time users receive continued but lessened effects from their device.[34][35] While one group study has reported continued overall reductions in stuttering after a year of daily use of the SpeechEasy on reading and a monologue task,[36] others have found that some participants showed adaptation effects, gaining less benefit from the device after exposure for several months, including stuttering more with the device than without it.[8][33] Some studies of various altered auditory feedback devices have noted carryover fluency, i.e. a reduction in stuttering after the stutterer removes an electronic fluency device,[27][29][33][37] while others have not.[9][36]

The effective of electronic fluency devices as measured by qualitative measures and ratings by stutterers have also been made. Studies show that some stutterers report improved fluency and confidence about speaking, and less severe stuttering and some carryover effects; the device is perceived as being particularly useful on the telephone.[8][33][38] They reported that the device was difficult to use in noisy situations as the device amplifies all voices and sounds,[8][34] and some acclimatization to the use of the device over time.[8] Qualitative reports of satisfaction may be disassociated from more objective measures of fluency: some stutterers who gain little or no benefit from a device based on objective measures rate the device highly, while others who were obtaining benefit on measures of fluency reported negatives opinions about the device.[8][33]

Use with children

There is little experimental evaluation of the therapeutic effect of AAF on children who stutter: one study noted that effects of FAF were less in children than adults.[39] Given the lack of evidence of its effectiveness, as well as concerns about the impact of altered feedback on developing speech and language systems, some authors have expressed the view that the use of an AAF with children would be unethical.[2]

Causes of altered auditory feedback effects

The precise reasons for the fluency-inducing effects of AAF in stutterers are unknown. Early investigators suggested that those who stutter had an abnormal speech–auditory feedback loop that was corrected or bypassed while speaking under DAF.[9] Later researchers proposed increased fluency was actually caused by the changes in speech production, including slower speech rates, higher pitches and increased loudness, rather than the AAF per se.[40][41] However, subsequent studies have noted that increased fluency occurred in some stutterers at normal and fast rates using DAF.[41][42] Some suggest that stuttering is caused by defective auditory processing, and that AAF helps to correct the misperceived rhythmic structure of speech.[43] It has been shown that some stutterers have noted that have atypical auditory anatomy and that DAF improved fluency in these stutterers but not in those with typical anatomy.[44] However, positron emission tomography studies on choral reading in stutterers suggest that AAF also made changes in motor and speech production areas of the brain, as well as the auditory processing areas. Choral reading reduced the overactivity in motor areas that is found with stuttered reading, and largely reversed the left-hemisphere based auditory-system and speech production system underactivation.[45][46] Noting that the effects of altered feedback vary from person to person and can wear off over time, distraction has also been proposed as a possible cause of stuttering reduction with AAF.[47]

References

  1. 1 2 Ward (2006) p. 300
  2. 1 2 3 4 5 6 7 8 9 10 11 Lincoln M, Packman A, Onslow M (2006). "Altered auditory feedback and the treatment of stuttering: a review". J Fluency Disord 31 (2): 71–89. doi:10.1016/j.jfludis.2006.04.001. PMID 16750562.
  3. ↑ Ingham RJ, Kilgo M, Ingham JC, Moglia R, Belknap H, Sanchez T (2001). "Evaluation of a stuttering treatment based on reduction of short phonation intervals". J. Speech Lang. Hear. Res. 44 (6): 1229–44. doi:10.1044/1092-4388(2001/096). PMID 11776361.
  4. ↑ Craig A, Hancock K, Chang E; et al. (August 1996). "A controlled clinical trial for stuttering in persons aged 9 to 14 years". J Speech Hear Res 39 (4): 808–26. doi:10.1044/jshr.3904.808. PMID 8844560.
  5. ↑ Hancock K, Craig A, McCready C; et al. (December 1998). "Two- to six-year controlled-trial stuttering outcomes for children and adolescents". J. Speech Lang. Hear. Res. 41 (6): 1242–52. doi:10.1044/jslhr.4106.1242. PMID 9859881.
  6. ↑ Ward (2006) p. 293
  7. ↑ Saltuklaroglu and Kalinowski (2006) p. 173-4
  8. 1 2 3 4 5 6 7 8 9 10 Pollard R, Ellis JB, Finan D, Ramig PR (April 2009). "Effects of the SpeechEasy on objective and perceived aspects of stuttering: a 6-month, phase I clinical trial in naturalistic environments". J. Speech Lang. Hear. Res. 52 (2): 516–33. doi:10.1044/1092-4388(2008/07-0204). PMID 18695013.
  9. 1 2 3 4 Stuart A, Kalinowski J, Rastatter M, Saltuklaroglu T, Dayalu V (2004). "Investigations of the impact of altered auditory feedback in-the-ear devices on the speech of people who stutter: initial fitting and 4-month follow-up". International journal of language & communication disorders / Royal College of Speech & Language Therapists 39 (1): 93–113. doi:10.1080/13682820310001616976. PMID 14660188.
  10. 1 2 3 4 Kalinowski J, Armson J, Roland-Mieszkowski M, Stuart A, Gracco VL (1993). "Effects of alterations in auditory feedback and speech rate on stuttering frequency". Language and speech 36 (1): 1–16. PMID 8345771.
  11. ↑ Stager SV, Denman DW, Ludlow CL (1997). "Modifications in aerodynamic variables by persons who stutter under fluency-evoking conditions". J. Speech Lang. Hear. Res. 40 (4): 832–47. doi:10.1044/jslhr.4004.832. PMID 9263947.
  12. ↑ Dewar, A, & Dewar, AD (1979). "The long-term use of an automatically triggered auditory feedback-masking device in the treatment of stammering". British Journal of Disorders of Communication 14 (3): 219–229. doi:10.3109/13682827909011361.
  13. ↑ Stuttering: A Brief Review
  14. ↑ Ward (2006) p. 298
  15. ↑ Ward, p. 48
  16. ↑ Saltuklaroglu and Kalinowski (2006), p. 239
  17. ↑ Ward, p. 49
  18. 1 2 3 Bothe AK, Finn P, Bramlett RE (2007). "Pseudoscience and the SpeechEasy: Reply to Kalinowski, Saltuklaroglu, Stuart, and Guntupalli (2007)". American Journal of Speech-Language Pathology 16: 77–83. doi:10.1044/1058-0360(2007/010). PMID 17329678.
  19. ↑ Kalinowski J, Stuart A (1996). "Stuttering amelioration at various auditory feedback delays and speech rates". European Journal of Disorders of Communication 31 (3): 259–69. doi:10.3109/13682829609033157. PMID 8944848.
  20. 1 2 3 Zimmerman S, Kalinowski J, Stuart A, Rastatter M (1997). "Effect of altered auditory feedback on people who stutter during scripted telephone conversations". J. Speech Lang. Hear. Res. 40 (5): 1130–4. PMID 9328884.
  21. 1 2 Stuart A, Kalinowski J, Rastatter M (1997). "Effect of monaural and binaural altered auditory feedback on stuttering frequency". Journal of the Acoustical Society of America 111 (6): 2237–41. doi:10.1121/1.1466868. PMID 9193064.
  22. 1 2 Armson J, Foote S, Witt C, Kalinowski J, Stuart A (1997). "Effect of frequency altered feedback and audience size on stuttering". European Journal of Disorders of Communication 32 (3): 359–66. doi:10.3109/13682829709017901. PMID 9474287.
  23. ↑ Kalinowski J, Stuart A, Wamsley L, Rastatter MP (1999). "Effects of monitoring condition and frequency-altered feedback on stuttering frequency". J. Speech Lang. Hear. Res. 42 (6): 1347–54. doi:10.1044/jslhr.4206.1347. PMID 10599617.
  24. ↑ Hargrave S, Kalinowski J, Stuart A, Armson J, Jones K (1994). "Effect of frequency-altered feedback on stuttering frequency at normal and fast speech rates". Journal of speech and hearing research 37 (6): 1313–9. doi:10.1044/jshr.3706.1313. PMID 7877290.
  25. 1 2 3 Ingham RJ, Moglia RA, Frank P, Ingham JC, Cordes AK (1997). "Experimental investigation of the effects of frequency-altered auditory feedback on the speech of adults who stutter". J. Speech Lang. Hear. Res. 40 (2): 361–72. doi:10.1044/jslhr.4002.361. PMID 9130204.
  26. 1 2 Armson J, Stuart A (1998). "Effect of extended exposure to frequency-altered feedback on stuttering during reading and monologue". J. Speech Lang. Hear. Res. 41 (3): 479–90. PMID 9638914.
  27. 1 2 Van Borsel J, Reunes G, Van den Bergh N (2003). "Delayed auditory feedback in the treatment of stuttering: clients as consumers". International journal of language & communication disorders / Royal College of Speech & Language Therapists 38 (2): 119–29. doi:10.1080/1368282021000042902. PMID 12745932.
  28. ↑ Ward (2006), p. 299
  29. 1 2 3 4 Armson J, Kiefte M, Mason J, De Croos D (2006). "The effect of SpeechEasy on stuttering frequency in laboratory conditions". J Fluency Disord 31 (2): 137–52. doi:10.1016/j.jfludis.2006.04.004. PMID 16753207.
  30. ↑ Bothe AK, Davidow JH, Bramlett RE, Ingham RJ (2006). "Stuttering Treatment Research 1970–2005: I. Systematic Review Incorporating Trial Quality Assessment of Behavioral, Cognitive, and Related Approaches". American Journal of Speech-Language Pathology 15 (4): 321–341. doi:10.1044/1058-0360(2006/031). PMID 17102144.
  31. 1 2 Finn P, Bothe AK, Bramlett RE (2005). "Science and pseudoscience in communication disorders: criteria and applications". Am J Speech Lang Pathol 14 (3): 172–86. doi:10.1044/1058-0360(2005/018). PMID 16229669.
  32. ↑ Hidalgo, Jason (2004-01-26). "Help for stutterers? Devices such as the SpeechEasy are growing popular due to exposure on shows like "Oprah," but experts say they may not be the miracle cures people expect". Reno Gazette-Journal. Retrieved 2007-12-02.
  33. 1 2 3 4 5 6 O'Donnell JJ, Armson J, Kiefte M (2008). "The effectiveness of SpeechEasy during situations of daily living". J Fluency Disord 33 (2): 99–119. doi:10.1016/j.jfludis.2008.02.001. PMID 18617051.
  34. 1 2 Davis, Robert (2004-10-18). "Those who stutter find hope". USA Today.
  35. ↑ Ward (2006), p. 296, 298
  36. 1 2 Stuart A, Kalinowski J, Saltuklaroglu T, Guntupalli VK (2006). "Investigations of the impact of altered auditory feedback in-the-ear devices on the speech of people who stutter: one-year follow-up". Disability and rehabilitation 28 (12): 757–65. doi:10.1080/09638280500386635. PMID 16754573.
  37. ↑ Radford NT, Tanguma J, Gonzalez M, Nericcio MA, Newman DG (2005). "A case study of mediated learning, delayed auditory feedback, and motor repatterning to reduce stuttering". Perceptual and motor skills 101 (1): 63–71. doi:10.2466/PMS.101.5.63-71. PMID 16350610.
  38. ↑ Kalinowski J, Guntupalli VK, Stuart A, Saltuklaroglu T (2004). "Self-reported efficacy of an ear-level prosthetic device that delivers altered auditory feedback for the management of stuttering". Int J Rehabil Res 27 (2): 167–70. doi:10.1097/01.mrr.0000128063.76934.df. PMID 15167118.
  39. ↑ Howell, P; Sackin, S; Williams, R (1999). "Differential effects of frequency-shifted feedback between child and adult stutterers". Journal of Fluency Disorders 24 (2): 127–136. doi:10.1016/S0094-730X(98)00021-7. PMID 18259595.
  40. ↑ Ward, 2006, p. 50
  41. 1 2 Sparks G, Grant DE, Millay K, Walker-Batson D, Hynan LS (2002). "The effect of fast speech rate on stuttering frequency during delayed auditory feedback". J Fluency Disord 27 (3): 187–200; quiz 200–1, III. doi:10.1016/S0094-730X(02)00128-6. PMID 12371347.
  42. ↑ Kalinowski J, Stuart A (1996). "Stuttering amelioration at various auditory feedback delays and speech rates". Eur J Disord Commun 31 (3): 259–69. doi:10.3109/13682829609033157. PMID 8944848.
  43. ↑ Harrington J (1988). "Stuttering, delayed auditory feedback, and linguistic rhythm". J Speech Hear Res 31 (1): 36–47. PMID 3352254.
  44. ↑ Foundas AL, Bollich AM, Feldman J; et al. (2004). "Aberrant auditory processing and atypical planum temporale in developmental stuttering". Neurology 63 (9): 1640–6. doi:10.1212/01.wnl.0000142993.33158.2a. PMID 15534249.
  45. ↑ Wu JC, Maguire G, Riley G; et al. (1995). "A positron emission tomography [18F]deoxyglucose study of developmental stuttering". NeuroReport 6 (3): 501–5. doi:10.1097/00001756-199502000-00024. PMID 7766852.
  46. ↑ Fox PT, Ingham RJ, Ingham JC; et al. (1996). "A PET study of the neural systems of stuttering". Nature 382 (6587): 158–61. doi:10.1038/382158a0. PMID 8700204.
  47. ↑ Ward, 2006, p. 57

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