Knowles Targets New Listening Response Curve for TWS Earphone Design
Knowles presented a new preferred listening response curve for earphone design at an AES Chicago Chapter meeting last week. True wireless stereo (TWS) earphone manufacturers have been “slow to take advantage” of the hi-res audio ecosystem, Knowles said. With more…
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hi-res music available from streaming services such as Tidal, Amazon Music HD and Apple Lossless -- and the availability of high data rate Bluetooth codecs -- the industry is now in a position to deliver hi-res audio wirelessly “with the right hardware and tuning,” Knowles said. The company analyzed over 200 recordings -- chosen from the past 20 years of the Billboard Hot 100 to represent much of the music that headphone wearers are likely to be streaming -- and found “significant high-frequency content above 10 kHz in popular music that many earphones fail to reproduce well.” It then conducted controlled blind testing with a variety of listeners across demographics and hearing abilities to determine what makes the best sound quality, as preferred by listeners. Optimum high-frequency response is key when designing hi-res earphones, the company said. Using recently developed technology, Knowles was able for the first time to extend an understanding of user preference beyond 10 kHz to create the Knowles Preferred Listening Response Curve. By focusing on high-frequency response, the new curve gives manufacturers insight to deliver the best hi-res listening experience, it said. Company research shows earphones tuned to earlier concepts of “what sounds good severely understate the amount of high-frequency energy that listeners prefer,” it said. The curve showed listeners consistently preferred between 12 and 21 decibels (dB) of boost at frequencies beyond 10 kHz, depending on age and hearing ability, Knowles said. Designing and tuning an earphone that matches the high-frequency boost identified using the Knowles curve is expected to consistently provide a highly satisfactory end-user experience and receive high ratings from consumers, it maintained. The curve could be a powerful tool when used with hearing personalization algorithms, enabling TWS earphone designers with hearing personalization software to configure their algorithm to produce optimum sound quality across the range of hearing abilities commonly experienced by consumers, it said.