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Articles September - October 2023

Capturing The True Essence Of Sound New!

From Lewitt Audio's Pure Tube Microphone to Sennheiser's Profile USB Microphone, these studio microphones offer precise audio quality to the users and deliver crisp, clear sound. read more

Articles September - October 2023

Photo Feature: Studio Showcase New!

From A.R. Rahman's studio in Mumbai to composer Raag Sethi's first Dolby-compliant studio in Gujarat, PALM Expo Magazine's Studio Showcase features the latest studios in India. read more

Articles September - October 2023

Mastering The Art Of Sound With Donal Whelan New!

Whelan talks to the PALM Expo Magazine Team and discusses his foray into the world of mastering, his unique experience at the PALM Conference 2023, and more. read more

Articles September - October 2023

Nx Audio Celebrates Two Decades Of Pro Audio Journey New!

Nx Audio completes 20 years of delivering pro audio products for the Indian pro sound industry. Read about Nx Audio's journey over the last two decades. read more

Articles September - October 2023

Mumbai Studio Explores New Verticals With Genelec Monitors New!

The combination of Genelec Smart Active Monitors and digital audio interface delivered an ideal monitoring solution for BOING Recording Studios. read more

Articles September - October 2023

IRAA Awards 2023: Jury Reflections New!

Read about IRAA Jury's perspective on the bigger questions in the music industry - AI for music production, the status of mega consoles, & emerging trends in sound recording & mixing. read more

Articles September - October 2023

Gray Spark Audio Opens New Studio For Academy Students New!

PALM Expo Magazine Team talks to Ronak Runwal to explore how the newly-designed Studio D is poised to become a recording haven for the academy students. read more

Articles September - October 2023

Firdaus Studio: Building A Sonic Paradise For Recording Artists New!

The Firdaus Studio by A.R. Rahman stands as a beacon of innovation in the music production industry. PALM Expo Magazine explores the making of the musical maestro's magnus opus in the recording landscape. read more

Articles September - October 2023

Naveen Deshpande Elevates Stand-Up Comedy with Bespoke Lighting Designs New!

Naveen Deshpande, a renowned lighting designer, made heads turn through his recent collaboration with India's leading stand-up comedian, Zakir Khan, during the latter's international tour. 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!


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