Virtual Bass As A Method For Reducing Listening Levels of Personal Listening Devices

Abstract

The popularity of personal listening devices (PLDs) has led to concerns of hearing damage sustained from their regular use at high listening levels. Bass perception plays an important role in the enjoyment of music, however, low-frequency output from many standard issue PLD earphones is severely limited by their small size. It was hypothesised that PLD users increase their listening levels to overcome the reduced low-frequency output of small PLD earphones. By increasing perceived bass at lower listening levels, PLD users may not need to increase listening levels to improve sound quality. Bass boost equalisation is currently the conventional method for improving bass levels, however, this approach can produce undesirable effects such as distortion and potential loudspeaker damage. Virtual bass processing is suggested as an alternative method for improving bass perception while still retaining desirable sound quality. To test this, participants were asked to listen to two different music samples; one standard track between all participants and one track chosen by them. Preferred listening level measurements were recorded in the participants’ ears while they listened (blind) to three differently processed versions of each track (original audio, virtual bass processing, and bass boost equalisation) in three different noise conditions (quiet, 65 dBA Leq “street noise”, and 85 dBA Leq “bus noise”). Participants were also required to judge preference in terms of overall sound quality and bass quality. The results showed a reduction in mean listening levels of 1.9 dB when virtual bass processing was applied to the original track in the quiet condition, but no reduction in either noise condition. Preference results showed that virtual bass processing was preferred by most participants in the majority of test conditions. It was concluded from this study that virtual bass processing is not a viable method for reducing listening levels of PLDs since no changes were measured in background noise, however, preference results suggest that virtual bass may improve sound quality of low cost PLD earphones.