###### Abstract  
As binaural audio continues to permeate immersive technologies, it is vital to develop a detailed understanding of the perceptual relevance of HRTFs. Previous research has explored the benefit of individual HRTFs with respect to localisation. However, localisation is only one metric with which it is possible to rate spatial audio. This paper evaluates the perceived timbral and spatial characteristics of both individual and non-individual HRTFs and compares the results to overall preference. To that end, the measurement and evaluation of a high-resolution multi-environment binaural Impulse Response database is presented for 20 subjects, including the KU100 and KEMAR binaural mannequins. Post-processing techniques, including low frequency compensation and diffuse field equalisation are discussed in relation to the 8802 unique HRTFs measured for each mannequin and 2818/2114 HRTFs measured for each human. Listening test results indicate that particular HRTF sets are preferred more generally by subjects over their own individual measurements. perception; evaluation; timbre; HRTF; binaural; spatial audio; measurement; database Article  
A Note that this paper is intended to be a reference for the subject of the paper. transfer function between a localised free-field anechoic source and the signals present at a listener's tympanic membrane (ear drum) [4]. Typical features include a time delay, spectral colourations caused by the shape of the pinnae and early reflections from the shoulders and torso. Alternatively, Binaural Room Impulse Responses (BRIRs) may be considered which include environmental contributions such as wall and floor reflections [5]. A particular transfer function, \(h(n)\), may be applied to a signal, \(s(n)\), by means of convolution [6] such that the output, \(y(n)\), may be written  
\[y(n)=\sum_{k=0}^{N-1}s(k).h(n-k).\]  
By convolving a signal with an HRTF or BRIR and presenting the result directly to a listener's ears (usually via headphones), a source may be simulated as if coming from the direction in which the Impulse Response (IR) was measured. The quality with which the source is rendered depends on the individual listener and the measurements used. Binaural IRs are a result of physiological features and as such are unique to an individual. Although certain characteristics may be generalised, for example, an increase in time delay as a source moves toward the contralateral hemisphere, other features such as the high frequency spectral notches caused by the pinnae are not so easily replicated. In this paper, we use the phrase _individual HRTFs_ to refer to the unique HRTF measurements of a particular person. We use this phrase in place of other commonly used terms (e.g., personal, personalized, individualized) in an attempt to discriminate between real-world measurements and alternative HRTF selection/optimization processes. The use of non-individual measurements alters the way in which a person perceives a sound. However, it is unclear as to whether this could benefit a listener [7; 8]. Previous studies focus extensively on the impact individual measurements have on source localisation [9; 10; 11; 12; 13; 14; 15] but fail to properly consider alternative perceptual implications. Considering the ever-growing market for binaural technology, it is necessary to consider the impact of using different binaural IRs more generally and within the context of competing rendering schemes [16; 17]. It is proposed in this paper that a listener's individual measurements may not be optimal in all cases. We find that within particular measurement sets exist listening attributes that are preferable to a wide range of subjects. As a result, the use of such sets over individual measurements may improve a person's listening experience. In this paper, we evaluate the performance of both individual and non-individual HRTFs. In a blind study, participants were asked to rate a series of mono, stereo and binaural stimuli based on four pre-defined spatial audio attributes.