Speech Intelligibility Versus Congruency: User Preferences of the Acoustics of Virtual Reality Game Spaces. Supplementary Data.

Abstract

3D audio spatializers for Virtual Reality (VR) can use the acoustic properties of the surfaces of a visualised game space to calculate a matching reverb. However, this approach could lead to reverbs that impair the tasks performed in such a space, such as listening to speech-based audio. Sound designers would then have to alter the room’s acoustic properties independently of its visualisation to improve speech intelligibility, causing audio-visual incongruency. As user expectation of simulated room acoustics regarding speech intelligibility in VR has not been studied, this study asked participants to rate the congruency of reverbs and their visualisations in 6-DoF VR while listening to speech-based audio. The participants compared unaltered, matching reverbs with sound-designed, mismatching reverbs. The latter features improved D50s and reduced RT60s at the cost of lower audio-visual congruency. Results suggest participants preferred improved reverbs only when the unaltered reverbs had comparatively low D50s or excessive ringing. Otherwise, too dry or too reverberant reverbs were disliked. The range of expected RT60s depended on the surface visualisation. Differences in timbre between the reverbs may not affect preferences as strongly as shorter RT60s. Therefore, sound designers can intervene and prioritise speech intelligibility over audio-visual congruency in acoustically challenging game spaces.

The article under the same name can be found in the journal Virtual Worlds.

Repository information

This repository contains supplementary materials to support the article. Details of the experiment process and the results of the data analysis can be found in the article.

"Aggregated Experiment Data.zip"

• Contains the aggregated experiment data as Excel workbooks. Each workbook contains documentation explaining the workbook's purpose and data types used.

"Speech stimuli.zip"

• Contains audio recordings of the stimuli used in the experiment captured at the listener's default position within the modelled room. Three rooms, labelled by surface material, are used in 4 versions, resulting in a total of 12 stimuli.
• Please be aware that the listener could move within the room and thereby adjust the level of direct sound.
• The audio is captured from Unity directly via a virtual audio loopback device using an RME Babyface sound card. The files are stored in the WAV format at 48 kHz@24 bits, stereo. They are recorded in binaural audio without headphone calibration. Binauralisation is achieved via Google Resonance Audio.
• Please use headphones to listen to them.
• The raw, un-reverberated, monaural speech test signal is also included.

"IRs.zip"

• Contains the binaural 2-channel impulse responses of the modelled rooms generated by a Dirac impulse captured at the listener's default position within the modelled rooms in binaural audio.
• Please be aware that the listener could move within the room.
• Three rooms, labelled by abbreviated surface material, are used in 4 versions with three measurements each, resulting in a total of 36 measurements.  The abbreviations are Blk = Concrete Blocks, Mrb = Marble, Fab = Fabric.
• The audio is captured from Unity directly via a virtual audio loopback device using an RME Babyface sound card. The files are stored in the WAV format at 48 kHz@24 bits, stereo. They are recorded in binaural audio without headphone calibration. Binauralisation is achieved via Google Resonance Audio.
• Please use headphones to listen to them.
• The archive also contains a TXT file documenting the whole capturing process of the IRs and a WAV file with the impulse used to create the IRs.

"Room Parameters.zip"

• Contains CSV files describing the room acoustical parameters of the rooms measured in IRs.zip.
• Each room's version has its own CSV file, resulting in a total of 12 files. The three measurements appear as separate channels.
• Angelo Farina's Aurora tools have been used to calculate these parameters following ISO 3382-1:2009.
• The archive also contains a TXT file documenting the whole capturing process of the IRs.

"Screenshots.zip"

• Contains screenshots of each experiment's stage, including all stimuli. Only one question of the questionnaires is captured here for brevity. The screenshots are captured within Unity using a non-VR camera.