Introduction

The process of separating voice from music in a recorded speech can be a complex task, especially when both are intertwined. This article aims to provide insights into the techniques and tools available to help achieve clear, understandable spoken content from a recording that also includes music. We delve into methodologies such as phase inversion, mid-side encoding, and the use of graphic equalizers to enhance the intelligibility of spoken words in a mixed audio environment.

Techniques for Audio Separation

The field of audio separation is a combination of signal processing and digital audio editing techniques. These techniques are designed to isolate the spoken word from the musical content, making the words clear and audible. Here are some of the methods described:

Phase Inversion

If you have an instrumental version of the song, one possible technique is phase inversion. By inverting the phase of the instrumental and summing it with the track that includes vocals, the music can be partially or completely canceled out, leaving the vocals. This method, while not perfect, can often significantly improve the clarity of the spoken content.

Mid-Side Encoding/Decoding

When you don't have an instrumental version, another approach is to use mid-side encoding and decoding. This involves converting the audio into a mid-side format, where the mid channel contains the vocals and the side channels contain the instrumental. By stripping out the side information, you can then use a graphic equalizer to further refine and isolate the spoken content. This process is not guaranteed to be perfect, but it can bring you close to your goal.

Graphic Equalizer

A more straightforward technique involves the use of a graphic equalizer. With a free Digital Audio Workstation (DAW) such as Audacity, which includes a built-in graphic equalizer, you can boost or cut frequencies to enhance the clarity of the spoken word. The typically effective frequency bands for spoken words range from 800Hz to 2000Hz, where boosting or cutting other frequencies can help in making the vocals more intelligible. Additionally, reducing low frequencies can help to diminish the background music, further clarifying the spoken content.

Academic and Architectural Insights

The separation of audio signals, particularly in complex sound environments like live music venues or public address (PA) systems, also falls under the broader field of intelligibility. Researchers like Dr. Toyoda, who designed the sonics for the iconic Walt Disney Concert Hall in Los Angeles, have contributed significantly to our understanding of sound design. His papers on intelligibility and sound architecture provide valuable insights into designing spaces that optimize the clarity of spoken words over musical backgrounds.

Conclusion

Separating the voices from music in a recorded speech is a challenging but achievable task with the right tools and techniques. Whether using phase inversion, mid-side encoding, or graphic equalizers, these methods can help improve the clarity and intelligibility of spoken content. Understanding the broader principles of audio separation and intelligibility can enhance your ability to edit and process audio recordings effectively.