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Things Audacity Can’t Do

I have been using Audacity, the free digital audio recorder and editor, for a long time. It’s a great program, but there are some things it can’t do, such as:

  • It can’t record or play files in the MIDI format.
  • If you want to play or export files in proprietary or restricted file audio formats such as WMA (Windows Media Audio) or AAC (Advanced Audio Coding, supported by iTunes, iPad, iPod, YouTube, and others) you have to download and install additional plug-ins.
  • It has less plug-ins and effects that a specialized Digital Audio Workstation (DAW).
  • It can’t apply sound effects in realtime. You have to record the track and then apply sound effects to it.
  • It isn’t a specialized audio editing software package. There are some limitations on multi-track editing and mixing features.

Despite these limitations Audacity is a powerful and easy-to-use application that probably will meet the needs of most people who want to record audio, do some basic editing, and add special effects to it. Please contact me if you have any questions about it.

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Getting Started with Digital Audio – What Equipment do I Need?

You need very little equipment to record digital audio. You will need a computer with a sound card. Unless you are a professional musician, or have some other special need, the sound card that came installed in your computer will probably work fine. Don’t even think about using the built-in mic on your computer or laptop or notebook computer for recording. The sound quality of your recording will be terrible. For $20-30 you can probably buy a desktop or headset microphone that will be adequate. I have aBlue Snowball Microphone Blue Snow Ball mic I bought from Amazon.com for $79 that I record a lot with. The audio quality of my recordings is pretty good, and my voice sounds natural. I also have a Sennheiser headset microphone I bought from Amazon for $170. I hate to have to admit this, but the Blue Snowball mic is just as good. If you have a microphone that did not come with a stand, you should buy one because you have to keep your mic steady to get a decent recording. That’s really all you need for recording audio except for a free software program such as Audacity for recording and editing. If you own an Apple computer it came with the Garageband audio program installed and it’s much more than adequate for anyone except a professional studio musician.

Getting Started with Digital Audio – What Equipment do I Need?

You need very little equipment to record digital audio. You will need a computer with a sound card. Unless you are a professional musician, or have some other special need, the sound card that came installed in your computer will probably work fine. Don’t even think about using the built-in mic on your computer or laptop or notebook computer for recording. The sound quality of your recording will be terrible. For $20-30 you can probably buy a desktop or headset microphone that will be adequate. I have a Blue Snow Ball mic I bought from Amazon.com for $79 that I record a lot with. The audio quality of my recordings is pretty good, and my voice sounds natural. I also have a Sennheiser headset microphone I bought from Amazon for $170. I hate to have to admit this, but the Blue Snowball mic is just as good. If you have a microphone that did not come with a stand, you should buy one because you have to keep your mic steady to get a decent recording. That’s really all you need for recording audio except for a free software program such as Audacity for recording and editing. If you own an Apple computer it came with the Garageband audio program installed and it’s much more than adequate for anyone except a professional studio musician.

Converter that “Converts” MP3 Files to WAV Files

I am working with a professor here at Cypress who is revising the Biology Self-Assessment Modules. She created a PowerPoint presentation and I let her borrow my new expensive headset microphone to record the audio for one of the modules. There was so much noise in the recordings they were not usable. I recorded the audio for each slide in Audacity using my Blue Snowball mic to see if it did a better job. The Blue Snowball did a good job. I exported each file from Audacity as an MP3 because an MP3 is about one tenth the size of a WAV file. I tried to embed the MP3s into the slides, but locked up my computer. I tried to do this on a computer in the FRC and locked up that computer also. I looked up this problem on the Web and learned that you cannot embed any type of audio into PowerPoint except WAV files. I have to embed the files, not link to them, because I am going to have to record the PowerPoint presentation in Camtasia and add some animation such as call outs to the slides.

I found that you can go to Source Forge.com and download a free converter called CDex that adds a special RIFF-WAV header to an audio file that will “fool” PowerPoint into thinking that the MP3 file is a WAV file. It changes the file extension from MP3 to WAV, but the file is the same size as the original MP3 file. I tried it and it works. You can download it here:

http://cdexos.sourceforge.net/?q=download . Be sure you download the Beta 1.70 version. I always use Firefox. It automatically checks each download for viruses.

You can find instructions on how to use the converter here:

http://www.addictivetips.com/windows-tips/how-to-embed-mp3-audio-files-in-microsoft-powerpoint-presentation/

I am going to post this message in the Digital Audio group also.

Workflow for Editing Audio in Audacity

I am currently working on a big audio editing project. I have found this workflow works good for me:

1. Listen to the clip, noting areas where this is nothing but noise.

2. Highlight an area that contains nothing but noise.

3. Open the noise removal tool and select Get Noise Profile.

4. Close the tool and select the entire audio clip.

5. Open Noise Removal again. I find it helpful to first remove 6 DB of noise. If the clip was recorded at a very loud level I remove 12 DB of noise. You can always remove more noise later.

6. Listen to the clip again, noting where clicking sound might be. Highlight each clicking sound and press the Delete key. Audacity has a tool that removes clicks, but I have found my method works better.

7. I always set Audacity so that if there is clipping on the track it is highlighted in red. Select the clipped areas and select the Clip Fix effect.

8. Normalize the clip if needed.

9. Export the MP3 file and save it in the location where you keep the files for this project.

Removing Noise with Audacity

I have been doing a lot of editing in Audacity recently, and mostly through trial and error, I have developed a workflow that works well for me. Today I am going to discuss how I remove noise from an audio clip. First, I open the clip in Audacity and listen to it. I have experimented with listening to cclips at different sound levels and I have found that setting the volume on my headset about halfway between the softest and the loudest levels works best. I look at the wave form and select a few seconds of noise.  The screen shot at the top shows what noise looks like. I open the Effect menu on the menu bar and select Noise Removal. On this screen I click the Get Noise Profile button to let the noise removal tool analyze  the sounds I want to remove from the clip. I return to the wave form and select all of it. I open the Noise Removal tool again and usually set it to remove 6 DB of noise. I never change the other two options, Frequency Smoothing and Attack/Decay time. I click the OK button to close this dialog box. I return to the clip and listen to it again. It works well for me if I remove noise in increments of 6 DB. If the clip was recorded at a very loud volume I remove 12 DB of noise. If you are too aggressive in removing noise the clip will have a hollow sound sort of like an echo chamber effect.

In future posts I will cover other auditing tasks in Audacity, such as removing clicks and clipping.

Getting Started with Audacity 1.3 by Bethany Hiitola

I just bought a book on Audacity 1.3, Getting Started with Audacity 1.3, by Bethany Hiitola. This book was published by Packt Publishing in 2010. In this book you will learn:

  • How to install the software and about all its main features
  • How to set up projects and how to record your first podcast
  • How to create MP3 podcasts from your saved projects
  • How to upload your podcast to your personal website or to iTunes
  • How to use all the audio effects that come pre-installed with Audacity
  • How to install and use Audacity plugins, such as Nyquist, LADSPA, and VST effects
  • About the toolbar, the menu, and keyboard shortcuts.

I have been using Audacity, the free audio editing program, for several years, and it is an excellent program that will meet the needs of almost everyone except audio professionals. Version 1.3 is the version I use. Version 2.0 was released in March 2012, but I have not downloaded it and started using it yet. Version 2.0 will be the topic of another post. As far as I know, no books have been published on Version 2.0, but you can view  the online manual at: http://manual.audacityteam.org/o/.

Radio Dead – Not So Fast

When I was growing up we did not have a TV in our house until I was about thirteen years old. If I wanted to be entertained I had to listen to the radio – AM radio. Radio has been around so long, almost 100 years, you may think it’s dead, but that is far from true. According to a survey by Arbitron, 93% of the respondents reported listening to, or at least owning a radio, in 2011. This is a decline of only 3% since 2001. The percentage of those surveyed doubled their use of online radio since 2001, 56% compared to 28%.
In 2011, one-third of all Americans (34%) said they listened to either streaming AM/FM versus internet-only services such as Pandora, or both, in the previous month.

Americans are a mobile people and we spend a lot of time in our cars, so lots of us spend a lot of time listening to radio while we are driving to work and for pleasure. In 2011, 11% of us listened to online-only radio while driving, compared to only 6% in 2010. This trend is especially popular among people aged 18 to 24. Today there are many mobile apps for listening to online-only services such as Spotify, Mogg, and Rdio. By 2015 about 75% of our population is estimated to be listening to music on their mobile devices. Of course many of them will not be listening to radio on their devices.

One of the latest trends in radio is HD, or high-definition, radio. In a survey conducted in 2010, Arbirton reported that only 7% of the respondents said they were very interested in HD radio. Clear Channel, which owns several hundred radio stations, and Cumulus Media are trying to bolster interest in this medium, but it’s too early to tell if they will be successful.

In 2011, mobile usage made up 70% of all usage of the Pandora service. The number of hours people listened to Pandora on mobile devices (164%) grew faster year by year than on laptop or desktop computers (12%). Three out of four people say they like or love satellite radio and that they like or love Pandora, but only 69% said they liked or loved traditional AM/FM radio. Pandora’s chief competitor is Spotify, a free European-based music-sharing company that was launched in 2008. Worldwide, Spotify has 10 million registered users; Pandora has 100 million in the United States alone, and 125 million total.

In 2011, Satellite radio had $2.7 billion in subscription revenue. This was up 7% over the previous year. The only company in the US satellite audio industry is SiriusXM, a service I use in my pickup. In 2011, Sirius reported nearly 21.9 million subscribers. In summary, current trends in radio point to the continued use of AM/FM radio, while the number of users decline due to increased use of radio on mobile devices, growth of services such as Pandora and Spotify, and increased growth of satellite radio, while HD radio faces an uncertain future.

(Source: Summary of article online by Laura Houston Santhanam, Amy Mitchell, and Tom Rosentiel or PEJ. Accessed at: http://stateofthemedia.org/2012/audio-how-far-will-digital-go/ ).

Bit Depth

In digital samples amplitude is represented as “bit depth.” Bit depth determines both the number of steps, or levels, that are possible in a sample and how loud a signal the system can tolerate. CD-quality sound uses 16 bits. We can calculate the number of steps by raising the number two to the 16th power. 2 ^ 16 = 65,536 steps. The number of steps is divided into 32,767 positive (plus 0) and 32,768 negative steps, representing the crests and troughs in a sample of music. Each time we take a sample of a piece of sound the actual amplitude must be rounded to the nearest available level, introducing something called a “quantization error.” Simply put, this means that a small amount of noise is produced each time a digital recording is sampled.

The next section will cover the signal-to-noise ratio, which is the amount of inherent noise versus the system’s capacity for the desired signal. In theory the overall capacity of a digital system is approximately six decibels per bit. For a 16-bit CD-quality a system can tolerate 96 dB. (Source: Cornell University Music Department. http://digital.music.cornell.edu/cemc/book/export/html/1594).

Illustration of bit depth

Sampling Rate

Sampling rates are measured in hertz (Hz) or cycles per second. This value represents the number of samples captured in order to represent the waveform. The more samples you take per second, the higher the sound quality. The human ear can hear sounds that fall approximately between 20 Hz and 20,000 Hz.

Capturing a sound at a particular frequency requires a sampling rate of at least twice that frequency. This frequency is known as the Nyquist frequency. If you want to capture sound within the range of human hearing, the sampling rate has to be at least 40,000 Hz. Capturing sound at higher rates than this is known as over-sampling. Aliasing occurs when a signal is sampled at sampled at less than twice the highest frequency present in the A sampling rate of 44,100 Hz is used for audio CDs. The most common sampling rates for audio are: 8 kHz, 16 kHz, 22.05 kHz, 22.25 kHz, 44.1 kHz, 48 kHz, 96 kHz, and 192 kHz. (Audacity manual and Wake Forest University).

Aliasing

Waveform with high and low sample rates