Room Acoustic Software Research Articles

Acoustic correction of monumental churches with ceramic material: The case of the Cathedral of Benevento (Italy)

In this work, soundproof systems for the acoustic correction of large spaces, such as monumental churches, are studied. The Cathedral of Benevento is considered as a case study. Dated back to the seventh century, the church was destroyed during the Second World War and rebuilt in the mid-twentieth century, using marble for the floor and smooth plaster for the side walls. In the current state, the cathedral exhibits an excessive reverberation time (about 10 s) that causes poor understanding of speech and not good listening to musical performances. It is difficult to perform any form of acoustic correction inside the cathedral, since the walls and the ceiling cannot be covered with traditional sound-absorbing material due to architectural and aesthetic reasons. Therefore, the possibility of using ceramic material applied to the side walls for the acoustic correction of low-frequency components and transparent micro-perforated sheets placed under the ceiling for the acoustic correction of medium- and high-frequency components are considered. The work is divided into three phases: in the first phase, measurement of the current acoustic characteristics of the cathedral is performed. In the second phase, sound absorption material is investigated and in the third phase, the effects of insertion of soundproof systems on the acoustic characteristics of the cathedral are theoretically evaluated by means of a room acoustic software.

Acoustic Characterisation by Using Different Room Acoustics Software Tools: A Comparative Study

Acoustic Characterisation by Using Different Room Acoustics Software Tools: A Comparative Study

Parametric design applications in architectural acoustics—Generation and optimization of reflective surfaces for specific source/receiver combinations

This investigation considers the potentials of what are normatively visual parametric design tools, within acoustics design thinking. The typical workflow inherent to most room acoustic software consists of architectural design followed by analysis. In response to the emergence of parametric tools in architectural design, like Rhino and Grasshopper, acoustic designers now have the potential to carry out some analysis through visualization in a more streamlined manner. Furthermore, parametric tools carry the capability to alter the typical workflow from “design followed by analysis” to a more integrated design and analysis workflow, or in some cases even a set criteria followed by a set of design solutions. Through investigation and application of these idea as a part of a recent Master of Architecture thesis project at Judson University, I have been able to develop and test specific parametric definitions which define and visualize reflecting surface potentials based on set source and receiver area criteria.

Comparisons between simulated and in-situ measured speech intelligibility based on (binaural) room impulse responses

This study systematically compares acoustic simulation and in-situ measurement in terms of speech transmission index (STI), speech intelligibility scores and relationship curves when considering (binaural) room impulse response and four general room conditions, namely, an office, a laboratory, a multimedia lecture hall and a semi-anechoic chamber. The results reveal that STI can be predicted accurately by acoustic simulation (using room acoustics software ODEON) when there is a good agreement between the virtual models and the real rooms and that different reverberation time (RT) and signal-to-noise ratio (SNR) may exert less significant influence on the simulated STI. However, subjective intelligibility may be overestimated when using acoustic simulation due to the head-related transfer function (HRTF) filter used, and the score bias may be minimal and difficult to detect in everyday situations. There is no obvious score tendency caused by different RT, though with the decrease in the SNR, score bias may increase. Overall, considering that the accurate acoustic modelling of rooms is often problematic, it is difficult to obtain accurate speech intelligibility prediction results using a simulation technique, especially when the room has not yet been built.

Perceptual thresholds for realistic double-slope decay reverberation in large coupled spaces.

Reverberation highly influences sound perception in enclosed spaces. The reverberation time (RT) metric, used to quantify reverberation in single volumes, is inappropriate for coupled spaces characterized by non-exponential double-slope energy decays. Previous research on reverberation perception of double-slope decays has been predominantly based on varying basic impulse response characteristics such as decay times corresponding to reverberation times of individual volumes presented as independent variables. Alternatively, several studies have employed geometrical room acoustic software simulations to generate collections of responses while varying architectural parameters such as coupling area and room volumes. To avoid issues related to geometrical acoustics simulations, such as position dependence and limitations of some software to properly simulate coupled volume behavior, this study examines perception of the variability of reverberation typical of a physical coupled volume system. Employing an established statistical model, the control parameter of coupling area aperture which acoustically connects the volumes serves as the independent variable. Two listening tests were conducted to determine perceptual thresholds using an ABX discrimination task. The range of tested values corresponded to physically realizable variations. Just noticeable differences (JNDs) were derived with an average JND of ≈ 10% variation of the coupling aperture. No significant differences were found between different musical excerpts.

From the sound up: Reverse-engineering room shapes from sound signatures

Typically, architects and acousticians design rooms for music starting from a model room shape known from past experience to perform well acoustically. We reverse the typical design process by using a model sound signature to generate room shapes. Our method builds off previous research on reconstructing room shapes from recorded impulse responses, but takes an instrumental, design-oriented approach. We demonstrate how an abstract sound signature constructed in a hybrid image source-statistical acoustical simulator can be translated into a room shape with the aid of a parametric design interface. As a proof of concept, we present a study in which we generated a series of room shapes from the same sound signature, analyzed them with commercially available room acoustic software, and found objective parameters for comparable receiver positions between shapes to be within just-noticeable-difference ranges of each other.

Investigating Room Acoustics by Simulations and Measurements

Measurements in room acoustics are often used as the true reference of reality, while simulations are considered to be only a crude representation of it. However, both approaches have their own challenges and limitations, so measuring an impulse response and deriving room acoustic parameters correctly may be more difficult than it appears at first glance. In this article we present the comparison between measurements and simulations for two real-case rooms: an auditorium and a cathedral. The comparison is made in the ODEON Room Acoustics Software version 121 and shows that careful postprocessing of the measured data can lead to high agreement with advanced room acoustics simulations. For a complete room acoustics study both measurements and simulations seem to be equivalently necessary.

Impact of design decisions on acoustical comfort parameters: Case study of Doğramacızade Ali Paşa Mosque

Acoustical design of mosques is critical considering speech and music related activity patterns held in such religious spaces. This paper aims to emphasize the importance of practicing acoustics of mosques as early as in the concept design stage. Within this framework, design issues of a contemporary mosque, namely, Doğramacızade Ali Paşa Mosque in Ankara, Turkey are discussed. The edifice known as the technological mosque with its eclectic interpretation has a unique architectural style. The architectural design of the mosque is heavily supported with acoustical design in all phases. Computer simulation is applied as an acoustical design tool and estimations are held by commercial room acoustics software. Results are justified with real size field measurements inside the mosque and related objective acoustical parameters including reverberation time (RT or T30), clarity (C50 or C80), speech transmission index (STI) and A-weighted sound levels (SPL-A) are assessed. Evaluation of the space indicates that the optimized acoustical field is proper for intended functions of use in a mosque and satisfies desired tranquil environment.

How the design of a balcony affects the acoustics in an auditorium?

A 3D-simulation for improving the acoustics in an auditorium was done using room acoustic software, Odeon. The software provides the sound field inside the hall and thus the sound propagation physics was studied. The 3D computer model was done based on an existing auditorium of over 1000 seats. Further simulations have been done by removing the balcony and changing it's the geometry. The effect of different balcony geometry on the sound quality inside the hall was estimated and compared. Apart from reverberant time, the effects on energy ratios and other parameters from simulation results were studied. [L. Y. Cheung is supported by the Hong Kong Polytechnic University.]

Auditory localization in realistic environments by normal-hearing and hearing-impaired listeners

The ability to correctly localize sounds is important for general awareness of the auditory scene and communication in adverse acoustic conditions. However, most localization studies are performed in rather simple and artificial conditions. In particular, very few studies have considered localization in reverberant environments or in the presence of complex interferers, and no studies have systematically investigated the effect of distance. In the present study, localization performance was therefore measured as a function of source-receiver distance using a virtual auditory environment. With increasing source-receiver distance the direct-to-reverberation energy ratio decreases and the auditory system increasingly relies on mechanisms related to the precedence effect. Both aspects may be particularly problematic for hearing-impaired listeners. The acoustics of a cafeteria was simulated with the room acoustic software ODEON for a large number of source-receiver locations. Signals were generated for a 3D ar...

Perception of scattering coefficient in auralized concert halls.

The scattering coefficient has become a determinant parameter in room acoustic software because it enhances the precision of simulation results. Although there is a wide agreement on the necessity of using scattering coefficients for characterizing surfaces and pattern elements within an enclosed space such as a concert hall, there is still a lack of knowledge on the influence of this on the human perception. The primary purpose of this study is to investigate how changes in scattering coefficients of diffusing surfaces could possibly affect the perception of music among the audience in concert halls. A simplified shoebox‐like geometry was used to generate binaural room impulse responses under various scattering conditions for different seats. Computer simulation results were convolved with sound examples, which were properly selected as representative of typical music textures. Results from listening tests will be shown and discussed.

3D 모델의 구체성이 건축음향 시뮬레이션 및 가청화시재에 미치는 영향

The present study examined the effects of the complexity of the 3D models on the results of acoustic simulation which is the predominant tool of the acoustical design of buildings. Also, the effects of the 3D model on the auralized sounds were investigated. In order to carry out the study, four 3D models with different levels of complexity were introduced for a real auditorium which have different numbers of surfaces in the persuit of the guidance of odeon room acoustic software. The set-up of models was also based on the level of transition order of the program. And the acoustic experiments were performed measuring room acoustic parameters including SPL, RT, C80, D50. Acoustic computer simulations were performed using four different models. Then, the results of the computer modeling were compared with the measured acoustical parameters. In addition, sound sources were recorded in the field and auralized sounds were made in convolution with the impulse source made from acoustic modeling. Then, subjective tests were undertaken using auralized sounds. As the results, it was found that the result of the acoustic simulation were closer to the real room acoustic properties when 3D model was more particularly made. For the subjective test, the listening materials were acknowledged as similar with the real sound source when more complex 3D model was used. Then, it could be concluded that the complexity of the 3D model affects the results of the acoustic modeling as well as subjective tests.

Gymnasium room acoustics. Comparisons of different metrics, criteria, measurements, and calculation methods (including acoustical modeling software).

Gyms are nondiffuse large boxes and have unusual room acoustics challenges related to safety, durability, and volume. Classic room acoustics analysis methods, such as that of Fitzroy and Sabine, measurements, as well as acoustical modeling software results are compared. Speech intelligility results from the room acoustics software are compared against traditional reverberation time criteria. What has been learned about criteria and calculation methods is shared.

Double Sloped Decay: Subjective Listening Test to Determine Perceptibility and Preference

Can music listeners, both experienced and inexperienced, distinguish a double-sloped decay from a Sabine decay? Do they prefer the double slope? A simulated space, based on an actual built coupled-volume hall, was conceived in room acoustics software to create double sloped and classic Sabine auralizations. The simulated decays were compared with in situ measurements taken in a built coupled volume concert hall for validation. The impulse responses generated were convolved with an anechoic musical recording, grouped in pairs, and played for subjects. Participants listened to the recorded pairs over headphones and were asked to determine (1) if the two recordings sounded different, (2) which recording was more likely to have a double slope or had a more dramatic double slope, and (3) which of the two recordings they prefer. The more a recording diverged from a standard Sabine decay, the more likely the respondents were to identify that recording as having a double slope. When asked to identify a preference, subjects were no more likely to select a recording with a double-sloped decay, than a Sabine decay.

Lessons learned from room acoustics design and investigation (especially from using EASE room acoustics software) in our consulting practice

Experiences troubleshooting during the design of new buildings and investigation of existing acoustical problems in existing buildings, including churches, dining spaces auditoria, public meeting spaces, offices, and rehearsal spaces. Lessons learned and experiences with tools, such as EASE room acoustics software. Theoretical concepts to consider in designing box shaped rooms, cafeterias, rehearsal spaces, and churches. Tools and methods to consider in acoustical investigations.

The ‘Franssen’ illusion for short duration tones is preattentive: A study using mismatch negativity

When a tone burst is divided into two parts, an onset transient and a sustained tone smoothly fading on, and these parts are delivered to two stereophonically located loudspeakers in a room, a listener gains the impression that the whole sound is coming from the loudspeaker that actually emits merely the transient. Due to this auditory illusion known as the ‘Franssen effect’ (FE), the physical and the perceived lateralizations of the sustained sound become different. A two-block mismatch negativity (MMN) paradigm was used to investigate the stage of auditory processing at which this segregation would take place. In one block, standard stimuli were 100 ms, 1 kHz tone bursts emitted by one of the loudspeakers, and deviant stimuli were their split version, with the sustained part switched to the other loudspeaker. In the other block, the roles of the two stimuli were swapped. A room acoustics software was used for generating the signals to a headphone. The responses recorded from 10 subjects displayed no MMN, although the same stimuli but without the transients evoked prominent MMNs. This indicated that the mechanism underlying this illusion modifies the neural representation of the stimulus with FE in such a way that it becomes similar to that of the stimulus without FE before reaching the input of the preattentive mechanism indexed by the MMN. Considering the possible relationship of this illusion to the precedence effect and also the relevant electrophysiological findings in the literature, we conclude that the primary auditory cortex is the most plausible site of the mechanism leading to the FE.

The effect of mean free path on reverberation room measurement of absorption and absorption coefficients

As diffusers are added to a reverberation chamber, the measured absorption of a sample increases. Often, absorption coefficients greater than one are measured, which is theoretically impossible. Edge diffraction is often offered as an explanation for these results. When diffusers are added, the mean free path (MFP) becomes shorter and therefore the sound waves hit the surfaces more often. This might be partially responsible for the increase in measured absorption as diffusers are added. Modern room-acoustics modeling software allows the calculation of MFP for any room configuration using ray tracing techniques. If the Sabine absorption equation were rearranged to leave in the MFP term, more accurate measurements of absorption might result.

Coupled volume/double slope subjective listening test

Can experienced listeners of music discern a double-sloped decay from a Sabine decay? Do they prefer the double slope? Concert hall designers use coupled-volumes and their signature double-slope sound decay in an effort to reconcile the inversely related qualities of reverberance and clarity. A simulated space, based on an actual built coupled-volume hall, was conceived in the room acoustics software CATT-Acoustic. Variations in the aperture sizes that sonically expose the main hall to the coupled volume generated both classic Sabine decays and double-sloped decays. The impulse responses generated were convolved with the same anechoic musical recording, grouped in pairs, and played for an opportunity-sample of 21 volunteers from the Architectural Acoustics section of the 145th meeting of the Acoustical Society of America in Nashville. Participants listened to the 11 recorded pairs over headphones and were asked to determine (1) if the two recordings sounded different, (2) which recording was more likely to have a double slope or had a more dramatic double slope, and (3) which of the two recordings they prefer.