Home Cinema Acoustics
The theatre or the basic listening-room is the final link in the audio chain leading to the musical and cinematic pleasures of a Home Cinema. To maximise the satisfaction serious listeners and cinema consultants go through a considerable trouble and expense in customising their ‘rooms’ acoustically. There are many, many variables and combinations in speakers and rooms that can affect what we hear.
While the room dimensions play an important role, it is true that a perfect cube or a long corridor make poor listening rooms - though there are many satisfactory shapes between these two extremes - the good thing is that almost any room can be made to sound good with the right kind of speakers’ selection, placement and acoustic treatment.
In the movie industry there are standards, contrary to the audio industry, and the ‘standards’ requires that the ‘listening-room’ be relatively dead or anechoic, so that the sense of ambience is provided by the multi channel sound track, which is reproduced through multiple speakers. The essence of a great Home Cinema is the dynamic range of the spatial experience.
In today’s cinema - or, more generally, multichannel ensemble - the aim is to be transported to a war zone, a closet, a corridor, a stadium, or wherever the script dictates, including the night-club or a brothel. In addition, one can be a voyeuristic witness to intimate whispers with no ambience sound whatsoever. For all these sound simulations to be effective, the ‘listening-room’ reverberations (Echo) must not dominate.
If the commercial acoustic material or devices - absorbers, diffusers, and so on - are well designed and effective at their intended task, the only issues then are the price and appearance. To have serious impact on reverberation, all-surface areas have to be covered. Small cushion-like devices are of little value for a multichannel system. The thicker the acoustical material, the more effective it is especially at low frequencies. But at the same time the high frequencies will die before reaching the last row ears starting from the front. Hence a gradual Controlled Sound Absorption is used judiciously, to ensure the high frequencies do not get absorbed before passing through each ear.
Of all this advice, the over-riding recommendation is to be patient and leave the rest to your Home Cinema consultant. In the end, every room and every system will have its own character. The human brain is a wonderfully adaptive organ, and with a little time adjusts to the complex acoustical filter that a room amounts to.
Good luck and happy listening!
- Dr. Himanshu Kumar, Mentor, Mini Theaters India.