The development and validation of the speech quality instrument

Objective

Although speech perception tests are available to evaluate hearing, there is no standardized validated tool to quantify speech quality. The objective of this study is to develop a validated tool to measure quality of speech heard.

Study Design

Prospective instrument validation study of 35 normal hearing adults recruited at a tertiary referral center.

Methods

Participants listened to 44 speech clips of male/female voices reciting the Rainbow Passage. Speech clips included original and manipulated excerpts capturing goal qualities such as mechanical and garbled. Listeners rated clips on a 10-point visual analog scale (VAS) of 18 characteristics (e.g. cartoonish, garbled).

Results

Skewed distribution analysis identified mean ratings in the upper and lower 2-point limits of the VAS (ratings of 8–10, 0–2, respectively); items with inconsistent responses were eliminated. The test was pruned to a final instrument of nine speech clips that clearly define qualities of interest: speech-like, male/female, cartoonish, echo-y, garbled, tinny, mechanical, rough, breathy, soothing, hoarse, like, pleasant, natural. Mean ratings were highest for original female clips (8.8) and lowest for not-speech manipulation (2.1). Factor analysis identified two subsets of characteristics: internal consistency demonstrated Cronbach's alpha of 0.95 and 0.82 per subset. Test–retest reliability of total scores was high, with an intraclass correlation coefficient of 0.76.

Conclusion

The Speech Quality Instrument (SQI) is a concise, valid tool for assessing speech quality as an indicator for hearing performance. SQI may be a valuable outcome measure for cochlear implant recipients who, despite achieving excellent speech perception, often experience poor speech quality.

Level of Evidence

2b. Laryngoscope, 2017

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