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Articles July-August 2020

Bay Owl Studios – Not Just Music by the Bay

Launched in February 2020, Bay Owl Studios was founded by Varun Parikh who is an audio engineer and had no significant musical influence while growing up. His first exposure to music came when he was in high school..... read more

Harman all the Way

India’s First Domestic Hotel Chain – the Luxurious MAYFAIR Lake Resort – hires Qubix Technologies to provide state-of-the-art, end-to-end Integration with HARMAN Professional Solutions. PT reports..... read more

ANGRIYA Cruises the Seas with Bose

Latest cruise ships are teaming with audiovisual technology designed to keep passengers awed and coming back for more. In this feature PT reports on the audio installation of one such cruise ship - The Angriya Luxury Cruise Liner..... read more

Sennheiser 75-year Milestone

June 2020 marked the 75th anniversary of the foundation of Sennheiser, one of the world’s leading manufacturers of headphones, loudspeakers, microphones and wireless transmission systems. Through these 75 years, Sennheiser..... read more

Adiyogi Divya Darshanam Continues to Raise Standards

Since it’s unveiling in 2019 by the President of India Shri Ram NathKovind, the Adiyogi Divya Darshanam has enthralled spectators from across the globe. In May this year, this one of its kind projection mapping..... read more

Shankar & Siddharth Mahadevan’s Lambodara Studios

In the March-June 2020 issue of PALM Technology, PT did a cover story on Shankar and Siddharth Mahadevan’s new studio Lambodara. Here are some more images of the new studio..... read more

Acoustic and Audio System Design for Small Rooms- Part 2

In part 1 of this series we defined a small room, introduced the concept of sound waves as they relate to phase shift and comb filtering, and even touched on the Haas (precedence) effect. In this article, we will talk..... read more

IRAA 2020 Goes Virtual

PALM expo’s concern to ensure safety from ongoing pandemic mandated cancelation of the 2020 edition of PALM expo and in the best interest of the industry and business, decided not to move forward with the expo in 2020, carrying forward the show to May 2021..... read more

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Acoustic and Audio System Design for Small Rooms - Part 1

By - Rahul Sharma, CEO, Menura Acoustic Labs In collaboration with Sound Wizard

Acoustic and audio system design for a “small room” can be extremely challenging, especially for critical listening applications like control rooms and reference home cinemas. It is vital to understand the relationship between system design and acoustics, and to accept that neither aspect can be designed in isolation without considering the needs and requirements of the other. In this six part educational series, we will outline many important “small room” design considerations and along the way demonstrate how to effectively tackle common acoustical and system design problems

Small Rooms

Let us start by defining a “small” room, firstly so that you aren’t utterly disappointed at the end of the series, and secondly because understanding the distinction between small and large rooms is the key to digesting the completely different design approaches to both. In an attempt to keep theory to a minimum, lets just say that small rooms are those where the room boundaries are close enough to create modal issues in the lower frequencies. Extensive low frequency absorption is usually required, and since the first reflections of sound from room boundaries reach the listener extremely quickly, a great deal of care must be taken to prevent early reflections from colouring the direct signal. As a rule of thumb, a room whose largest dimension is under 20m or 65 ft can be considered to be a small room

In the first part of this series, we will focus on three basic acoustic and psychoacoustic phenomena whose understanding are critical to effective design; the Haas effect, comb filtering and phase shift.

Fig.1: The Haas Effect

Haas Effect

The simplest way to describe the Haas effect is through its other name, the precedence effect. If two sources of sound are separated in arrival time by less than approximately 40ms, they are perceived as one. Because of this, both sounds also appear to come from the same location, which ends up being the physical location from which the first sound reaches your ears. Because of this powerful psychoacoustic phenomenon, your brain locks into this physical location, and it then becomes very difficult for your brain to reset and convince itself that there are in fact two separate sources of sound in different locations.

Either the level of one has to be reduced significantly, or it has to be delayed by over 40ms. The implication of the Haas effect in small rooms is straight forward; your brain is unable to separate the direct signal from early reflections because the arrival times are too close together! Why is this bad? The short answer is comb filtering, but the concept of phase shift needs to be understood before we openthat can of worms.

Fig.2: Amplitude, Time Period and Frequency of a Wave

Phase Shift and Comb Filtering

As audio professionals, most of us are aware that every audible (and inaudibile) frequency has a corresponding wavelength. The time period defines the time it takes for one complete oscillation over that wavelength. While most audio signals are complex and never resemble a sine wave, we will still use one to illustrate our concept.

In the image below, two audio signals with the same amplitude (level), frequency response and wavelength BUT different arrival times have been added. Because of the different arrival times, the combination of constructive and destructive interference results in the “combing” you see in the image below. As you can imagine, this is not a desirable result.

Fig.3: Combing

The time delay created a phase shift in the wave, which combined with the original signal. Thanks to the Haas effect, this is the resultant wave we hear in a room. We sometimes mistakenly attribute the resultant wave to the audio system alone, when in fact it is a combination of the room and source. The colouration affects the spectral content of the sound waves, which goes against the main design goal of any listening space – transparency. The solution is to create a reflection-free zone, both through acoustic treatment and/or angling the walls of the listening room. Stay tuned as we dive deeper into acoustic and audio system design considerations for “small” rooms!