The Effect of Frequency Transposition on Speech Perception in Adolescents and Young Adults with Profound Hearing Loss

Abstract

This paper reports on a clinical trial evaluating outcomes of a frequency-lowering technique for adolescents and young adults with severe to profound hearing impairment. Outcomes were defined by changes in aided thresholds, speech perception, and acceptance. The participants comprised seven young people aged between 13 and 25 years. They were divided into two groups based on their audiometric configuration. The first group consisted of four young people with pure tone thresholds of 100 dB at 1 kHz. The second group had more profound hearing loss, with pure tone thresholds of >100 dB at 1 kHz. All participants attended the Fundació Widex Audiologia in Barcelona, a charitable foundation offering intervention and habilitation programmes for hearing-impaired children of all ages. The participants were oral communicators integrated into mainstream high schools and universities. All were experienced hearing aid users with excellent spoken language and no other disability. The hearing aids were fitted using standardized procedures and were worn with the frequency transposition algorithm in the first programme for consistent everyday use. Phoneme and word recognition were assessed after 4, 8, and 12 weeks of use and compared with results for their own superpower hearing aids. Subjective comments from both the participants and their parents were recorded throughout the study. Notable improvements were observed in both sound-field-aided thresholds and speech perception after 12 weeks of use, suggesting that frequency lowering can be efficacious in improving speech perception in severely to profoundly hearing-impaired individuals who are past the critical age for language acquisition.

The effects of frequency lowering on speech perception in noise with adult hearing-aid users

“…Methods used include manufacturer default settings (e.g., Gou et al, 2011; McCreery et al, 2013), detection of /s/ (e.g., Auriemmo et al, 2009), maximizing audibility with the Verifit band-passed speech (e.g., Glista et al, 2009; Wolfe et al, 2010; 2011), SoundRecover fitting assistant (Alexander, 2013; McCreery et al, 2013; McCreery et al, 2014), listener preference (e.g., Bohnert et al, 2010), and edge frequency of dead regions (e.g., Robinson et al, 2007). Few studies have comparatively evaluated each fitting method.…”

“…However, improvements with FL for this type of stimuli may overestimate the magnitude of improvement and generalizability (McCreery et al, 2014). Other studies have evaluated word recognition (Gou et al, 2011; McDermott et al, 2000;) while others have measured sentence recognition (Souza et al, 2013; Bohnert et al, 2010; Wolfe et al, 2010), which has the advantage of assessing the perception of multiple speech sounds within one trial (Hochmuth et al, 2012) and has better real-world validity. The American English Matrix Sentence Test in Noise was chosen to evaluate speech understanding in noise because it was designed to have high sensitivity to audibility changes and reliability, while maintaining real-world generalizability through the use of sentences.…”

“…Some studies have found that individuals with greater high frequency hearing loss are more likely to benefit from FL (Glista et al, 2009, Gou et al, 2011), while other studies have concluded the opposite (Simpson et al, 2006; McDermott & Dean, 2000). Our participants had gradually sloping hearing loss, and did not show significant improvements in speech perception with FL; therefore, our data is consistent with the hypothesis that individuals with less severe high frequency hearing loss will not benefit from FL.…”

“…Although studies on FL do not always demonstrate improved speech recognition, multiple studies investigating the use of this technology in adult and pediatric populations with hearing impairment have reported significant perceptual benefits compared to conventional amplification (Simpson et al, 2005; Alexander et al, 2008; Auriemmo et al, 2009; Kuk et al, 2009; Glista et al, 2009; Wolfe et al, 2010; Gou et al, 2011; Alexander, 2012; McCeery et al, 2012, 2014). Most studies to date compared each FL technology to a condition without FL.…”

“…Most studies to date compared each FL technology to a condition without FL. While the methodologies have varied, in general studies have shown benefit in quiet and noisy environments with FL activated compared to conventional processing (Simpson et al, 2005, 2006; Auriemmo et al, 2009; Galster et al, 2011; Glista et al, 2009; Kuk et al, 2009; Bohnert et al, 2010; Robinson et al, 2007; McCreery et al, 2014; Wolfe et al, 2010; Gou et al, 2011). However, mixed findings among participants in the same study and across studies have complicated the matter of determining how and when to use FL (McCreery, 2012).…”