Stuttering inhibition via altered auditory feedback during scripted telephone conversations

Abstract

Background

Overt stuttering is inhibited by approximately 80% when people who stutter read aloud as they hear an altered form of their speech feedback to them. However, levels of stuttering inhibition vary from 60% to 100% depending on speaking situation and signal presentation. For example, binaural presentations of delayed auditory feedback (DAF) and frequency-altered feedback (FAF) have been shown to reduce stuttering by approximately 57% during scripted telephone conversations.

Aims

To examine stuttering frequency under monaural auditory feedback with one combination of DAF with FAF (COMBO-2) and two combinations of DAF with FAF (COMBO-4) during scripted telephone conversations.

Methods & Procedures

Nine adult participants who stutter called 15 local businesses during scripted telephone conversations; each condition consisted of five randomized telephone calls. Conditions consisted of (1) baseline (i.e. non-altered feedback), (2) COMBO-2 (i.e. 50-ms delay with a half octave spectral shift up), and (3) COMBO-4 (i.e. 200-ms delay and a half octave spectral shift down in addition to the COMBO-2). Participants wore a supra-aural headset with a dynamic condenser microphone while holding a receiver to their contralateral ear when making telephone calls.

Outcomes & Results

Stuttering was significantly reduced during both altered auditory feedback (AAF) conditions by approximately 65%. Furthermore, a greater reduction in stuttering was revealed during the COMBO with four effects (74%) as compared with the COMBO with two effects (63%).

Conclusions & Implications

Results from the current study support prior research reporting decreased stuttering under AAF during scripted telephone conversations. Findings that stuttering was significantly reduced to a greater extent under the COMBO with four effects condition suggest that second signals reduce stuttering along a continuum. Additionally, findings support prior research results of decreased stuttering frequency under AAF during hierarchically difficult speaking situations. Clinical application of these findings may be that people who stutter can use specific software or smartphone applications that produce second speech signals to inhibit stuttering frequency effectively during telephone conversations.

http://onlinelibrary.wiley.com/doi/10.1111/1460-6984.12053/full

Delayed auditory feedback in the treatment of stuttering: clients as consumers

Abstract

Purpose: To investigate the effect of repeated exposure to delayed auditory feedback (DAF) during a 3-month period outside a clinical environment and with only minimal clinical guidance on speech fluency in people who stutter. Method: A pretest-post-test design was used with repeated exposure to DAF during 3 months as the independent variable. Nine stuttering individuals aged between 18 and 45 years served as subjects. Videotaped samples from different speech tasks were collected before and after 3 months' exposure to DAF, each time under two conditions: first during non-altered feedback (NAF) and subsequently during DAF.

Results: Before the repeated exposure to DAF, the percentage of stuttered words was significantly higher during NAF than during DAF. After 3 months‘ exposure to DAF, the percentage of stuttered words during NAF had dropped to a non-significant level in comparison with the DAF condition. Comparison of the percentage of stuttered words during NAF before and after repeated exposure to DAF showed significantly less stuttering after the repeated exposure to DAF. The percentage of stuttered words during DAF was generally somewhat higher, but not significantly so, after the 3 months’ repeated exposure to DAF than before the exposure to DAF.

Conclusions: Results confirm that DAF is an effective means of reducing stuttering even when employed as the only treatment approach outside a therapeutic environment. They also suggest that DAF continues to promote fluency when used over a longer period, but also that length of exposure and fluency enhancement are probably not in a linear relationship.

http://onlinelibrary.wiley.com/doi/10.1080/1368282021000042902/full