A virtual symphony orchestra for studies on concert hall acoustics

Traditionally, concert hall acoustics is evaluated by listening to live concerts, which makes a direct comparison challenging. This thesis presents new tools and methods in the domain of the room acoustics evaluation, studies, and auralization. Auralization stands for the process of rendering an existing or modeled acoustic space in a way that it can be presented to the listener as he/she was listening to a sound inside the space under study. An essential topic in this thesis is a framework for studying room acoustics with a wide-area loudspeaker array. The proposed loudspeaker orchestra consists of a number of loudspeakers that are positioned in the shape resembling a symphony orchestra on a stage. The acoustics can be evaluated in-situ by playing back anechoic signals, or in laboratory conditions via convolution of the impulse responses measured from the loudspeaker orchestra. The presented method enables a direct comparison of concert halls and it has been successfully applied in practice in several research articles. The principal requirement for such a loudspeaker orchestra is anechoic signals of high quality. For this purpose, a method and implementation of a system for recording the symphony orchestra instruments individually is presented. As the result, a selection of anechoic orchestral music is obtained with perfect channel separation. The recordings, intended for advancing the research on acoustics and auralization, are published for academic use. Directivity of the orchestra instruments in performance situation is investigated with anechoic measurements. The results for different instruments can be compared against each other or applied directly into auralizations. Data from the directivity measurements is also applied in the objective analysis of the presented loudspeaker orchestra. Furthermore, the implemented measurement system is utilized in investigating the sound radiation of the balloons, which are often used in room acoustic measurements. Related to the anechoic recordings, a novel approach to creating an impression of a group of musicians from a single recorded player is proposed. The method is mainly based on the video and audio analysis of the temporal differences between orchestra string players. The method is particularly beneficial with the anechoic recordings, where recording an instrument section is not possible, and recording a large number of musicians individually is time-consuming. The listening test results show that the presented method provides a plausible simulation of an instrument section sound in comparison to an industry-standard method

Virtual acoustics in practice rooms

Musiikin harjoitusluokkien pienestä koosta johtuen akustiikkasuunnittelussa joudutaan usein tekemään kompromisseja jälkikaiunnan ja tarvittavan vaimennusmateriaalin määrän suhteen. Harjoittelua ja instrumentin ääntä tukevaa sointia silmälläpitäen olisi suotavaa, ettei huone olisi kaiunnaltaan täysin kuiva. Kaiuttomassa tilassa soittaminen käy nopeasti raskaaksi ja saattaa vähentää aloittelevien soittajien harjoitteluintoa. Jälkikaiuntaa pieneen tilaan tavoiteltaessa joudutaan perinteisin akustisin menetelmin vähentämään vaimennuksen määrää, mikä puolestaan nostaa tilan äänitasoa. Varsinkin musiikin opettajien pidemmät altistusajat hyvin kaiuntaisissa opetusluokissa saattavat johtaa kuuloon liittyviin ongelmiin. Orkesterien tilanne on usein samankaltainen, kun harjoituksia joudutaan varsinaisen konserttisalin sijasta järjestämään akustisesti sopimattomissa tiloissa. Tässä työssä tutkitaan sähköakustisen järjestelmän käyttöä harjoitustilojen akustiikan parantamiseksi. Tarkoituksena on näin ollen lisätä jälkikaiuntaa nostamatta tilan äänitasoa. Tavoitteena on myös tutkia käyttäjien suhtautumista sähköakustiikan käyttöön. Työssä esitettyjä tutkimuksia varten sähköakustista järjestelmää kokeiltiin yhteensä kolmessa tilassa. Tutkituista tiloista kaksi ensimmäistä olivat tyypillisiä musiikkioppilaitoksen pieniä harjoitus- ja opetusluokkia. Kolmas tila oli monikäyttösali, johon sähköakustiikan avulla pyrittiin luomaan konserttisalin lavaa muistuttava akustiikka sinfoniaorkesterin harjoitusta varten. Tiloissa tehtiin huoneakustisia mittauksia sekä haastateltiin käyttäjiä kyselytutkimuksella. Tutkimusten tulosten perusteella on todettavissa, että harjoitustilojen akustiikan parantaminen sähköakustisella järjestelmällä on mahdollista.Due to their small size, the acoustical design of music practice rooms at music institutes presents designers with challenges and requires compromises between absorption and reverberation. In practice, some reverberation is needed to provide support and more lively sound for the musician. Playing in a room with plenty of absorption and very little reverberation is often uninspiring and easily causes fatigue. On the other hand, increasing reverberation by reducing the absorption results in higher sound pressure levels. As music teachers are exposed to these conditions for long periods of time, in the long term this can lead to hearing problems. Similar problems are often also faced by orchestras when rehearsals are held in facilities with poor acoustical conditions. This work investigates the use of an electro-acoustic system to improve the acoustics in practice spaces. The electro-acoustic system uses an active method to create additional reverberation without increasing the sound pressure levels. A second objective is to evaluate the acceptance of virtual acoustics by users in music practice spaces. For this purpose, a prototype of an electro-acoustic system was installed in three different rooms, and the reverberation time and sound pressure level of the rooms were measured. These case studies consist of two small classrooms and a theater hall converted to a rehearsal hall for a symphony orchestra. For each case study, subjective opinions were collected. The results for each room were then analyzed in terms of the feedback from the users. The case studies show that with a careful tuning, and especially in larger spaces, a virtual acoustic system is a potential solution for improving the room acoustics of a practice room

Proportion of effects by head-related transfer function and receiver position variation to interaural cross-correlation values

Interaural cross-correlation coefficient (IACC) is an objective room-acoustic parameter associated with the spatial impression and subjective quality of the acoustics. This study investigates the proportion of effects on the IACC variance simultaneously by (1) varied head-related transfer function (HRTF) and (2) locally varied receiver positions. The early IACC80 values are estimated from the binaural room simulations in eight room-acoustic conditions varying in room shape, side wall absorption, and receiver distance. Analysis across the combinations of HRTF and receiver positions indicates that below 2 kHz, around two-thirds of total IACC variance is explained by the receiver displacement, and at higher frequencies the HRTF variations dominate the IACC variance.Peer reviewe

Uncertainty in tuning evaluation with low-register complex tones of orchestra instruments

The relationship between perceived pitch and harmonic spectrum in complex tones is ambiguous. In this study, 31 professional orchestra musicians participated in a listening experiment where they adjusted the pitch of complex low-register successively presented tones to unison. Tones ranged from A0 to A2 (27.6–110 Hz) and were derived from acoustic instrument samples at three different dynamic levels. Four orchestra instruments were chosen as sources of the stimuli; double bass, bass tuba, contrabassoon, and contrabass clarinet. In addition, a sawtooth tone with 13 harmonics was included as a synthetic reference stimulus. The deviation of subjects’ tuning adjustments from unison tuning was greatest for the lowest tones, but remained unexpectedly high also for higher tones, even though all participants had long experience in accurate tuning. Preceding studies have proposed spectral centroid and Terhardt’s virtual pitch theory as useful predictors of the influence of the envelope of a harmonic spectrum on the perceived pitch. However, neither of these concepts were supported by our results. According to the principal component analysis of spectral differences between the presented tone pairs, the contrabass clarinet-type spectrum, where every second harmonic is attenuated, lowered the perceived pitch of a tone compared with tones with the same fundamental frequency but a different spectral envelope. In summary, the pitches of the stimuli were perceived as undefined and highly dependent on the listener, spectrum, and dynamic level. Despite their high professional level, the subjects did not perceive a common, unambiguous pitch of any of the stimuli. The contrabass clarinet-type spectrum lowered the perceived pitch.Peer reviewe

Architectural Features That Make Music Bloom in Concert Halls

The purpose of this paper is to spark discussions on the recent trends of designing vineyard and surround-type concert halls. We understand that these halls could be architecturally unique and many conductors like them, however, as outlined in this paper, they do not always serve the best for music acoustically. The motivation for visual proximity is easily understandable, but it should not overrule the acoustical conditions. We hope that this paper helps designers of new concert venues. We also hope to see more research and discussion on the acoustical qualities of these modern concert halls.Peer reviewe

Auditory Spatial Impression in Concert Halls

This chapter discusses the acoustics of concert halls from the viewpoint of binaural perception. It explains how early reflections have a crucial role in the quality of sound, perceived dynamics, and timbre. In particular, the directions from which these reflections reach the listener are important for human spatial hearing. The chapter has strong links to psychoacoustical phenomena, such as the precedence effect, binaural loudness, and spaciousness. The chapter discusses which aspects of a concert hall give listeners the impression of intimacy and the perception of proximity to the sound. Moreover, it is explained how a concert hall can change the perceived dynamics of a music ensemble. Examples are presented using measured data from real concert halls.Peer reviewe

Effect of inharmonicity on pitch perception and subjective tuning of piano tones

Funding Information: This research was supported by the Academy of Finland Project No. 289300, Niilo Helander Foundation, and Alfred Kordelin Foundation. The authors express their thanks to the piano tuners Harri Tuovinen (for a description of the aural tuning method), Elisa Visap€a€a (for contribution in development of the tuning experiment), and Matti Kyllonen (for assistance in the Steinway D grand piano recording session). Publisher Copyright: © 2022 Acoustical Society of America.The consensus in piano tuning philosophy explains the stretched tuning scale by the inharmonicity of piano strings. This study aimed to examine how variable inharmonicity influences the result of the piano tuning process, compare the tuning curves of aurally tuned pianos with the curves derived from subjective octave enlargement experiments, and evaluate whether the pitches of inharmonic or harmonic versions of the same tone are perceived differently. In addition, the influence of strings of other piano keys on the measured inharmonicity of a single piano string was investigated. The inharmonicity of all individual strings was measured on a Steinway D grand piano. Variable inharmonicity was implemented by additive synthesis with frequency-adjusted sinusoidal partials. Fifteen piano tuners and 18 orchestra musicians participated in the experiments. The results indicate that the inharmonic piano tones produced a keyboard tuning curve similar to the Railsback curve and differed significantly from the harmonic counterpart. The inharmonic tuning curve was reminiscent of the subjective octave enlargement curve. Inharmonic tone pitches were perceived to be higher than harmonic tones up to C » 7. The covibrating strings of the other keys did not exhibit any meaningful effect on the measured inharmonicity of a single string of the played key.Peer reviewe

Absorption of gilding in concert halls

A few renowned concert halls have walls, statues, and ceiling surfaces covered at least partially with gilding. Despite its appearance, such material is not actually gold. Instead, it is composition gold, which is a very thin leaf of copper-tin-zinc alloy, finished with shellac lacquering. In order to investigate the effect of treatments on room acoustics, we asked an artisan, a Master Gilder, to prepare gypsum cylinders that were pre-cut to diameter of 29 mm for impedance tube measurement. The top surfaces of these specimens were treated either with composition gold, real 24 carat gold leafs without shellac, or linseed oil paint. The absorption coefficients of all these cylinders were measured with an impedance tube. Each specimen was measured on both sides to provide a direct comparison between different surface treatments to untreated gypsum. This paper describes the measurement process, the practical issues encountered in fitting the specimens tightly for measuring, and finally the results of the measurements. The results show that the absorption coefficient of the composition gold is 0.02 over a wide frequency range, and it absorbs approximately 50% less sound energy than bare gypsum

Perception of music dynamics in concert hall acoustics

Dynamics is one of the principal means of expressivity in Western classical music. Still, preceding research on room acoustics has mostly neglected the contribution of music dynamics to the acoustic perception. This study investigates how the different concert hall acoustics influence the perception of varying music dynamics. An anechoic orchestra signal, containing a step in music dynamics, was rendered in the measured acoustics of six concert halls at three seats in each. Spatial sound was reproduced through a loudspeaker array. By paired comparison, naive subjects selected the stimuli that they considered to change more during the music. Furthermore, the subjects described their foremost perceptual criteria for each selection. The most distinct perceptual factors differentiating the rendering of music dynamics between halls include the dynamic range, and varying width of sound and reverberance. The results confirm the hypothesis that the concert halls render the performed music dynamics differently, and with various perceptual aspects. The analysis against objective room acoustic parameters suggests that the perceived dynamic contrasts are pronounced by acoustics that provide stronger sound and more binaural incoherence by a lateral sound field. Concert halls that enhance the dynamics have been found earlier to elicit high subjective preference.Peer reviewe