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Let’s define a podcast recording studio. A podcast recording studio is really a vocal room. It is a room where the voice is the instrument we are recording within the room. Voice and the frequencies and amplitudes associated with voice must be our priority when we are addressing the issues of a podcast recording studio. What are the frequencies associated with voice? Will these frequencies fit into the room we have chosen as our podcast recording studio. We need to examine the frequency and amplitude of the voice we will be using within our room and then decide what sound quality we want to treat the room to produce. If it is male voice, we may want to produce a sound quality that is clean and defined at all frequencies. If we are using a female voice in our podcast recording studio, we will need to decide how we want the female voice to be portrayed to the people receiving the content.

In a podcast recording studio, we have a table and a microphone in the usual set up. Sometimes the individual will want to stand up during their presentation. If the individual wants to stand and sit at a table during the presentation, we must design the room to allow for both these scenarios. If standing is going to be a delivery method, then we will need to make sure we have an adequate ceiling height to allow for proper speech intelligibility to occur without room distortion. To decide all of these variables, we look to a speech intelligibility index for guidance. A speech intelligibility index defines how many words we can hear within a sentence that is spoken. As you can see from the index below, a 30% comprehension level is bad. A 75% comprehension level is excellent. What within our podcast recording studio we produce distortion that will not permit us to achieve good speech intelligibility.

Reverberation Definition: https://www.dictionary.com/browse/reverberation

Reverberation is defined as how long a sound stays around within a room after it is spoken or played using an instrument. Reverberation is also the summation of all of the reflections from the wall surfaces within our podcast recording studio. Every surface within our room has reflections that bounce off each surface area. These reflections are room distortion. The direct sound or straight line sound from the voice to the microphone is our main concern. This direct sound is the cleanest sound we can have. However, the reflections from the wall surface areas interfere with the direct sound from source to microphone. Our goal is to minimize the impact these reflections have on our voice and thus speech intelligibility. Remember our goal is to hear 75% of all the words that are spoken or sung. We also want the microphone to be able to “hear” without the reverberation times from the room are too high.

To treat reverberation times, we must cover a certain percentage of the walls and ceiling with the proper rate and level of absorption material. This surface area coverage requirement is determined by formulas which we can then use to match the acoustic reverberation time goal with the room usage. If we are using our room for voice, we will want a reverberation time of around 1 second. Reverberation time preferences are subjective. some prefer a more reverberate room or lively room. Some will prefer a more dry or “dead” room. The reverberation times need to be dialed in over time, experience, and usage. One also must decide how much signal processing you are going to use on the voice. If delay and reverb are going to be added to the vocal then we need to start with a dry room so the electronics can do their thing without the room adding or subtracting from the equation.

For treatment, we must use absorption. With voice we can not use any type of sound absorption material. We must choose a technology that was specifically developed for music and voice. Our Studio Pro Foam took 8 years and 2M to develop. It is designed specifically for music and voice. It has the proper rates and levels of absorption that reduces the strength of the reflection from the wall and slows it down before it reaches the microphone. The foam must have a smooth response curve that does not over absorb at some frequencies and under absorb others. As you can see from the performance graph below, we have a smooth almost linear absorption rate from 125 Hz. – 1K. It is this linearity that engineers label “organic”. Most engineers that use our foam for voice state that they never touch the vocals right out of the gate. They place them in the mix as is and may add a little reverb or delay to get them to sit better in the mix but that is all the processing they will use with our foam.

Performance Comparison of Acoustic Fields Foam

Studio Pro Foam: https://www.acousticfields.com/product/acoustic-foam/

About Us At acoustic Fields: https://www.acousticfields.com/about/

Dennis Foley

Author Dennis Foley

I am an acoustic engineer with over 30 years’ experience in the business. My technology has been used in Electric Lady Land Studios, Sony Music of New York, Cello Music and Films founded by Mark Levinson, and Saltmines Studios in Mesa, Arizona, along with hundreds of others.

More posts by Dennis Foley

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