Sound Proofing and Room Acoustic Basics

Ah, sound proofing... a term which is thrown around by newbie sound guys who have heard of it but don't necessarily know what it means. They may have heard something about egg boxes, seen really expensive studio setups or heard of some funny stuff like bass traps, suspension ceilings and the like. This one's for you little ones (Don't be offended - I was in your shoes just a few years ago).

First off, let's define the difference between sound proofing and room acoustics.

• Sound proofing: This is essentially the method of isolating any sound from getting in or out of a space/room.
• Room Acoustics: This deals with getting a room to sound good by using materials within the room to dampen reverb/echo and flatten out the room's frequency spectrum.

I hope you're starting to see the difference, a sound proof room can sound really bad inside and a room which has been acoustically treated can still let sound leak in and out of it.

With that said, let's ask the next question: How can I improve sound proofing and room acoustics cheaply and effectively? To answer this, I will start with sound proofing and then deal with room acoustics separately.

Sound Proofing

The only way of stopping sound from escaping or entering a room is to isolate the room from the noise source. Sound can escape from a room in two ways: either directly through an air gap or indirectly by vibrating the medium between the room and the noise source (i.e. a window vibrates quite easily and thus even when it is closed will still transfer some sound). The best sound proofing method which is used by most professional studios is to build double walls with an air gap between them. This is also expensive and thus not relevant to cheapos like us. A cheaper way of doing this is to modify an existing room by sealing all the doors, windows and anything else which provides a gap for sound to travel through. Sound is able to get through very small gaps so covering the bottom of the door and even keyholes can make a significant difference. I have sealed my doors and windows with a weather proofing foam tape. The idea is to seal any gaps which connect the inside and outside of the room. It also helps to use really think curtains or wood to cover the windows as this will also create an air gap between the windows and the room.

Room Acoustics

Sound proofing is the easy one, because it is just about sealing things and going big. Room acoustics is more difficult because if you go too wild, your room will sound bad.

There are two major materials used to better a room's sound: absorbers (soft things like mattresses, carpets, sofas, etc) and diffusers (rough things like egg boxes, randomly loaded bookshelves, etc). Absorbers stop reflections by absorbing the higher frequency sound energy whilst diffusers still reflect sound but the reflection is scattered, making it harder to hear it as a defined echo. The easiest way to think of it is to use the analogy of light. A beam of light will reflect clearly off a straight piece of tin foil but when the same beam is shone onto a crumpled piece of tin foil, the light is reflected randomly around the room. In the case of the crumpled tin foil, the whole room should become brighter just like when you use diffusers, the room fills with a warm sound as opposed to a clear echo.

With that said, please don't go out and make the same mistake most rookies do. Most rookies hear this and decide to cover their entire room with absorbers and diffusers - i.e. a room covered from floor to ceiling in carpet. This is not ideal, you want your room to sound natural and enhance your recordings - reverb is a good thing if it is controlled. You control the room's sound by placing these materials in planned places around the room. This is a complicated process and I'd bore you to death if I wrote it all in one post, so I will just throw around some thought provoking ideas and then fill in the gaps in a future post. Idea 1: Focus on eliminating the corners, because corners amplify bass and muddy sound. Idea 2: If working in a room with parallel walls, place absorbers or diffusers on one wall only to eliminate sound waves bouncing back and forth. Idea 3: A thick carpet on the floor always helps. Idea 4: A bookshelf loaded randomly with books can act as a cheap diffuser. Idea 5: Read this awesome article: Acoustic Treatment for Home Studios. Idea 6: Keep reading my blog for other tips because I'm not finished with you :).

Other posts you might find interesting:
Monitor/Speaker Placement
Sound Mixing Tips: Bringing an Instrument Out of the Mud
What Gives a Guitar its Tone?
Sound Mixing Tips: High There?!
Sound Mixing Tips: Panning for Gold

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Hydrogen Drumbeat Templates - A Non-drummer's Best Friend

How do you know the stage is level?

...the drummer is drooling out of both sides of his mouth.

Yeah, yeah... I've heard them all. I know as a non-drummer it is very difficult to think like a drummer. Especially when most non-drummers reckon that drummers don't have the capability of thinking much :). However, to make a decent sounding drumbeat from a drum machine, you need to "think" like a drummer.

This can be quite a task, but don't fear! I, as a drummer, have done the thinking for you and made a bunch of Hydrogen beat templates which you can simply piece together to make a drumbeat. The concept is simple - all I have done is made a Hydrogen Song using various rock patterns. You can download this song and simply rearrange the patterns to suit you. Below is a link to the first beat template I have made:

BriansBeatsROCK.h2song (217 kB)
Note: These songs require the YamahaVintageKit available for download from here.

It consists of several basic 4/4 rock beats with a few fills. There is also a crash and drag pattern which can be overlaid on any of the pieces in order to pimp them. This sounds a bit weird but I have made an example song which shows just how easily these beat templates can be used. This can be downloaded from the link below:

ROCKBeatsExample.h2song (217 kB)
ROCKBeatsExample.mp3 (747 kB)

I have only used a closed hi-hat for the right-hand rhythm, however it is easy enough to interchange this with whatever suits you, like the ride, open hats, or crash. This is just my first attempt at beat templates. If I feel they are successful I will make more templates to suite the various genres such as Punk, Metal, Jazz, Funk, Latin and Pop. So please let me know by means of commenting on this post if you find these templates useful.

Other posts you might find interesting:
Hydrogen Drumbeat Templates: FUNK Beats
Hydrogen Drumkits
My Attempt at a Hydrogen Drumkit
Pimp my Hydrogen Beats
Making a Roll Sound Realistic
Sunday Bloody Sunday Hydrogen Beat

Audio Recording in Ubuntu Studio - Part 2: Record a Hydrogen Drumbeat

Okay, so you've planned your recording project like I told you to do in Audio Recording in Ubuntu Studio - Part 1: Plan your Project. You now want to create a Hydrogen drumbeat as the backbone to your track.

To begin, start up JACK and then Hydrogen. You can begin messing around with beats and patterns to get a feel for the program. If you want a more in depth description of the Hydrogen interface check out this post: Hydrogen Drum Machine Basics.

If you are unsure of the drumbeat that you will use for the song, just write a simple one and loop it for the entire song. As long as it is set at the same timing and at the same tempo, you can replace the beat with a better one at a later stage. A useful tip to remember: always start the beat off with a count-in, it will make the recording process a lot easier and you can always remove it later. For our recording project, we are using a Hydrogen beat for U2's song: Sunday Bloody Sunday - it is available for download here: Sunday Bloodly Sunday Hydrogen Drumbeat.

Once you have finished your beat, and you can play along to it in Hydrogen, you want to record it into Ardour. So start up Ardour and create a project with whatever name makes you sleep better at night. The Ardour interface should have only one track called Master. All the future tracks will be linked to the Master bus and then output to your soundcard. You now want to create enough tracks to record your drumbeat into. Hydrogen can either output one stereo track or a stereo track for each instrument/drum. I prefer to use multiple outputs, because it's more versatile - but if you are just laying down a simple beat, rather use the single stereo output (it is easier). I explain how to enable multiple outputs in Hydrogen in this post: Multiple Outputs for Hydrogen.

To add a track in Ardour, click on File and select Add Track. A window appears which allows you to chose how many tracks you want to add and whether those tracks are going to be stereo or mono.

If you are using Multiple outputs, select mono and add about six tracks. You can then change the names of the tracks by clicking in the track name and typing what you like. Use relevant names like snare, kick, crash, etc. it will only make it easier for you later.

If you are using just one stereo output, select stereo and add one track only. Name it Drums.

You now need to connect the Hydrogen outputs to the Ardour inputs, you do this from JACK. Open the JACK connections kit by clicking on the Connect button. This looks like the below figure.


Expand the Hydrogen tab under Outputs and the Ardour tab under Inputs. You now need to connect the relevant drum outputs to the inputs of Ardour. The Hydrogen outputs are unfortunately labeled as numbers, so you have to look in Hydrogen and determine which number links to which drum. Pan each Hydrogen instrument/drum fully to the left from the Hydrogen mixer. Then link only the left output of the instrument to the mono Ardour input.

Once all your connections are linked up correctly, you can start recording. Go back to Ardour and change the tempo so that it is the same as that found in Hydrogen. You can change it by double-clicking on the number (just above the Master track) and typing in the relevant tempo. You must now arm all of the tracks by clicking on the red circle found by each track's name (Only armed tracks will be recorded to). Once all the tracks are armed, select the Record Button (red circle) on the Ardour transport bar and then select the Play button - Ardour is now recording any activity in the armed tracks. Quickly go back to Hydrogen and click the Play button. If you observe the tracks in Ardour, you will see the drum waves being recorded. When the song is finished, press the Stop button in Ardour. Your Ardour project should look something like the below figure.


Your drumbeat has now been captured into Ardour and you can leave Hydrogen behind. It is important to drag your recorded drumtrack into time with Ardour's time, if you don't, Ardour's click track will not be in time. This is done by clicking on the drumtrack and dragging it till it aligns with the bar lines of Ardour. In Audio Recording in Ubuntu Studio - Part 3: Adding Effects to the Ardour Drumtrack, I will be discussing how to add effects to your drumbeat in Ardour.

Other posts you might find interesting:
Audio Recording in Ubuntu Studio - Part 1: Plan your Project
Sunday Bloody Sunday Hydrogen Beat
Hydrogen Drumkits
Pimp my Hydrogen Beats
Making a Roll Sound Realistic
Hydrogen Drumbeat Templates - A Non-drummer's Best Friend