Clinical trial NCT07020728: Clarity in Motion Phase-1 Perceptual Study of Speech Intelligibility
Official title: Speech Intelligibility and Listening Effort
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Healthy
Lead sponsor: Speech Technology and Applied Research Corp.
Sponsor class: INDUSTRY
Collaborators: name: National Institute on Deafness and Other Communication Disorders (NIDCD)
name: University of Cincinnati
First posted: 2025-06-13
Enrollment: 72
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: Subjects in each arm heard different treatments (interventions) of the same set of target words (spondees). Subjects in all arms heard the same spondees (but with different treatments), and subjects in all arms heard stimuli with all treatments (but different spondees).
Primary purpose: BASIC_SCIENCE

Brief summary: Participants will undergo a bilateral pure-tone hearing screen administered by a clinically trained member of the research team (either the PhD student or Dr. Boyce). The threshold criteria will be 20 dB SPL at 250 and 500 Hz, and 25 dB SPL at 1000, 2000, 4000, and 8000 Hz. All potential participants who fail the hearing screen will be provided with information about its meaning and referral for further audiological testing.

Participants who pass the hearing screen and other inclusion criteria will be divided into 6 groups, each of which will be presented with 144 stimuli equally distributed among processing conditions (Pristine Non-Moving Speech plus QoS Levels 1-5). Listeners will self-identify a comfortable listening level using supplied headphones and will be able to control the rate of presentation. There will be a short practice session. For each stimulus, listeners will be asked to transcribe the target sentences, and the intelligibility of each stimulus will be estimated by determining the mean percentage of content words correctly transcribed. After transcription, listeners will also be asked for two qualitative judgments using a visual analog scale: (1) the "clarity" of the stimulus, and (2) the "listening effort" involved. These measures are sensitive to situations where listeners manage to extract the uttered words from the signal, but with increasing difficulty (Beltyukova et al., 2008; Johnson et al., 2015). The quality of each stimulus will be estimated by the median quality judgment, and the effort likewise. Listening sessions will take place in a quiet room and presentation will be controlled by the Superlab presentation software program (already available in Dr. Boyce's lab).

The Stimuli will consist of audio recordings of target spondaic words embedded in a carrier sentence produced by a male and a female native speaker of American English recorded under quiet conditions. Each stimulus presented to the listeners for identification will be either unmasked pristine speech or will have been processed using our MIX and SMR algorithms in one of five ways with different mixtures of noise and sensor movement. The latter are identified as QoS Levels 1-5. Each type of processing is expected to have a different effect on the underlying probability that the listener will be able to correctly identify the spoken word, the effort required to do so, and the quality of the presented recording. Data on familiarity ratings for the target spondaic words and relative intelligibility of the two speakers under different conditions of noise masking has been previously reported (Goldhor et al., 2012).

Collectively, the estimates of word intelligibility, clarity, and listening effort under the different conditions will shed light on the effectiveness with which the tested algorithm preserves listener intelligibility with acceptable effort and quality.

Detailed description: Participants will undergo a bilateral pure-tone hearing screen administered by a clinically trained member of the research team (either the PhD student or Dr. Boyce). The threshold criteria will be 20 dB SPL at 250 and 500 Hz, and 25 dB SPL at 1000, 2000, 4000, and 8000 Hz. All potential participants who fail the hearing screen will be provided with information about its meaning and referral for further audiological testing.

Participants who pass the hearing screen and other inclusion criteria will be divided into 6 groups, each of which will be presented with 144 stimuli equally distributed among processing conditions (Pristine Non-Moving Speech plus QoS Levels 1-5). Listeners will self-identify a comfortable listening level using supplied headphones and will be able to control the rate of presentation. There will be a short practice session. For each stimulus, listeners will be asked to transcribe the target sentences, and the intelligibility of each stimulus will be estimated by determining the mean percentage of content words correctly transcribed. After transcription, listeners will also be asked for two qualitative judgments using a visual analog scale: (1) the "clarity" of the stimulus, and (2) the "listening effort" involved. These measures are sensitive to situations where listeners manage to extract the uttered words from the signal, but with increasing difficulty (Beltyukova et al., 2008; Johnson et al., 2015). The quality of each stimulus will be estimated by the median quality judgment, and the effort likewise. Listening sessions will take place in a quiet room and presentation will be controlled by the Superlab presentation software program (already available in Dr. Boyce's lab).

The Stimuli will consist of audio recordings of target spondaic words embedded in a carrier sentence produced by a male and a female native speaker of American English recorded under quiet conditions. Each stimulus presented to the listeners for identification will be either unmasked pristine speech or will have been processed using our MIX and SMR algorithms in one of five ways with different mixtures of noise and sensor movement. The latter are identified as QoS Levels 1-5. Each type of processing is expected to have a different effect on the underlying probability that the listener will be able to correctly identify the spoken word, the effort required to do so, and the quality of the presented recording. Data on familiarity ratings for the target spondaic words and relative intelligibility of the two speakers under different conditions of noise masking has been previously reported (Goldhor et al., 2012).

Collectively, the estimates of word intelligibility, clarity, and listening effort under the different conditions will shed light on the effectiveness with which the tested algorithm preserves listener intelligibility with acceptable effort and quality.

Eligibility criteria: Inclusion Criteria:

* Inclusion criteria will include adult native speakers of American English with auditory thresholds within age-normal limits, defined as passing a pure tone screening test of 20 dB SPL at 250 and 500 Hz, and 25 dB SPL at 1000, 2000, 4000, and 8000 Hz. Exclusion criteria will include self-report of hearing difficulties and failure to pass hearing screen.

No special populations requiring special protections will be utilized in this study. Potential participants who fail the hearing screen will be provided with results and appropriate clinical referral as per the IRB protocol.

Exclusion Criteria:

* Exclusion criteria will include self-report of hearing difficulties and failure to pass hearing screen.

Primary outcomes:
measure: Word Identification
timeFrame: Immediately after hearing the carrier phrase.
measure: Listening Effort
timeFrame: Immediately after hearing the carrier phrase.
measure: Naturalness of speech
timeFrame: Immediately after hearing the carrier phrase.
Secondary outcomes:
Other outcomes:
Locations:
city: Cincinnati
country: United States
facility: University of Cincinnati
state: Ohio
Study officials:
affiliation: Speech Technology & Applied Research Corp.
name: Richard S Goldhor, PhD
role: PRINCIPAL_INVESTIGATOR
References: