The importance of high-frequency audibility with and without visual cues on speech recognition for listeners with normal hearing

Abstract

Objective: To examine the impact of visual cues, speech materials, age and listening condition on the frequency bandwidth necessary for optimizing speech recognition performance. Design: Using a randomized repeated measures design; speech recognition performance was assessed using four speech perception tests presented in quiet and noise in 13 LP filter conditions and presented in multimodalities. Participants’ performance data were fitted with a Boltzmann function to determine optimal performance (10% below performance achieved in FBW). Study sample: Thirty adults (18–63 years) and thirty children (7–12 years) with normal hearing. Results: Visual cues significantly reduced the bandwidth required for optimizing speech recognition performance for listeners. The type of speech material significantly impacted the bandwidth required for optimizing performance. Both groups required significantly less bandwidth in quiet, although children required significantly more than adults. The widest bandwidth required was for the phoneme detection task in noise where children required a bandwidth of 7399 Hz and adults 6674 Hz. Conclusions: Listeners require significantly less bandwidth for optimizing speech recognition performance when assessed using sentence materials with visual cues. That is, the amount of bandwidth systematically decreased as a function of increased contextual, linguistic, and visual content.

Key Words::

• Frequency bandwidth
• speech recognition
• low-pass filtering

Declaration of interest: The authors declare no conflicts of interest.