Direct sound is defined as the portion of a sound wave which travels the shortest distance from the source to your ear. Everything else you hear after that initial split-second is due to reflection and reverberation. You actually receive more reflected sound than you probably realize. If the path from your ear to the speaker is obstructed, then most everything you hear is reflected sound. A certain amount of reverberation is pleasant because it contributes to a sense of envelopment, the feeling that sound is coming from all around you and not one single source.

The reverberant level is relatively constant throughout a loud room, yet the level of the direct sound decreases quickly as you move away from the speaker. The reverberant level is constant because it is composed of millions of non-correlated reflections, whereas the level of the direct sound is highly dependent on your distance from the source. Thus, when you are close to a speaker, the direct sound dominates, but as you move further away there is a point where the reverberant sound level becomes louder that the direct sound. The point where the direct sound level meets the reverberant level is known as the critical distance. One reason why an outdoor concert can sound vastly different than the same show indoors is because there is less reverberant sound, although sound engineers consider this when designing a system.

At a live concert, the critical distance could also be referred to as the proverbial “sweet spot”. Clarity is higher within the critical distance, yet envelopment is better outside of this distance. Thus, the best of both worlds is found along the critical distance. In well designed halls, the mixing board is placed at or near the critical distance so that the engineer can hear both the sound coming from the speakers and the sound that is bouncing around the room. So how can you determine where the critical distance is?

In large, reverberant rooms such as Webster Hall, the critical distance is relatively close to the speakers. In smaller halls and those with sound absorbing surfaces, the reverberant level is lower and the critical distance is further from the stage. This is the case with Mercury Lounge, where you are more aware of the placement of the speakers. The beautiful thing about Bowery Ballroom is that the speakers are raised high off the ground and many people are able to stand at a pleasant sounding distance from them. The balconies on the sides are thin and do not hinder the distribution of sound greatly.

One of Webster Hall’s problems is caused by the balconies, which are very wide. This forces the speakers towards the center of the room and causes many variations between different locations in the hall. I’ve enjoyed the sound from the center of the floor but in few other areas of the room. Webster also has other issues, such as the uneven frequency response. When I saw Wolf Parade recently there was one note on the synthesizer that always sounded much louder than the rest. This wasn’t due to the instrument, but rather one of the resonant frequencies of the room. Based on the dimensions of the room, certain notes are reinforced because their waves fit well between the walls and floor. You might notice this phenomenon if you stand over the sink in the bathroom and hum various notes. At least one note always sounds louder than the rest because its wavelength fits the size of the sink and it gets reinforced. The difference between the linoleum tile in Webster and the wood floor in Bowery is also worth noting. Wood absorbs more sound than concrete or linoleum and helps to shorten the reverberation time, improving clarity.

I’ve attempted to calculate the critical distance in a few clubs, but my figures are very rough estimates. You may find that it helps to be aware of the concept without being overly scientific about it. The only acoustic measurement devices that should really matter to concertgoers are attached to the side of their head.

This semester I am enrolled in Advanced Musical Acoustics and to be honest, I didn’t expect to learn very much in the class. After three semesters of physics I figured I’d had all the waves I could handle. But then we got into pyschoacoustics, alternate tuning systems, critical bands (the complex way your ear processes sound) and my favorite topic – room acoustics. Since learning just how much the size, shape and surfaces of a room contribute to the overall sound experience, I haven’t heard anything the same way. Each time I walk into a room I’m tempted to snap my fingers and estimate the reverberation time. Yeah… dork. So what does this have to do with indie rock? Glad you asked.

For the past month I’ve been studying the acoustics of various New York City rock venues and for my term paper I have chosen to compare Mercury Lounge, Bowery Ballroom and Webster Hall (The Bowery Presents Menage a Trois). It’s not a secret that Webster has worse acoustics in comparison to Bowery, but why? Bigger venues sound worse right? Well, not necessarily. There are some places in Webster where the sound can be very good for a given performance. (That’s right! You may be able to survive The National’s bump from Bowery). Also, it’s an arguable point, but I find the sound in Bowery Ballroom to be, on the whole, better than the smaller Mercury Lounge. In most venues, the sound quality depends where you stand, but the sound in the Bowery Ballroom is great pretty much anywhere. Turns out there’s a very good reason for that (coming up in part II).

I shall attempt to explain not only why these halls have their unique sonic characteristics, but also show you how moving just a few feet can drastically alter your concert experience. But first, a few definitions. I’m sure these terms seem obvious to many concert-goers, but relating subjective experiences to specific words makes it easier to compare different venues or various locations within a venue.

Intimacy – From an acoustic standpoint, this is the sense that the music is being played in a small room. Of course, visual cues play a big part in the intimacy of a performance and cannot be ignored.
Clarity/Definition – The degree to which individual sounds stand out from each other. Important for understanding vocals.
Envelopment – Envelopment is at a high level when the sound appears to arrive from all directions. It is the sense of being “drowned in sound”.
Reverberation – The level of sound which remains after its source has stopped. In a rock club, reverberation typically “builds” to a certain level since the sound source is relatively constant.

Without getting into too much detail, here are a few general (if obvious) tips. For increased reverberation and envelopment, move away from the speakers. For increased intimacy and clarity, get closer to the speakers. However you should try to stay between the left and right speakers so that the sound appears to be centered. For instance, when standing in the front left corner of Mercury Lounge – just in front of the speaker – the sound does not seem to be coming from the singer on stage and in my mind, detracts from intimacy.

In the next installment of Indiecoustics I’ll get a little more technical and attempt to explain how you can find the best sounding spot in any hall for a given band. I’ll also show you why Bowery Ballroom has such great uniformity, while a concert experience in Webster Hall can vary greatly depending on where you stand.

Note: Sound is perceived differently by every single person and my definition of “good sound” is sure to be different from yours. And you can probably find your favorite spot without my help. I simply hope to make everyone more aware of the elements which affect live sound and give you ideas about how to make them work in your favor. It’s one thing to know why Webster sounds like crap but it’s even better to know what you can do about it. It’s also nice to know whether you should blame the band, their engineer, the venue or your own vantage point for a terrible-sounding concert.