Audiobook Requirements
(FOR INTERNAL USE ONLY)
ACX Quality Control Document
Dear Colleagues,
As part of our commitment to producing high-quality audiobooks that meet industry standards and exceed our customers’ expectations, it is essential that all audiobook files processed by Whisperboy adhere strictly to the following internal guidelines. These instructions are designed to align with both ACX (Audiobook Creation Exchange) requirements and our internal standards of excellence to ensure the smoothest possible listening experience for our audience. Please read through the expanded guidelines carefully, as they contain vital details for ensuring that our audiobook files meet the professional quality that Whisperboy is known for. These guidelines are enforced and reviewed by the Whisperboy Audiobooks QC Team to ensure customer satisfaction.
1. Audio File Specifications
- Format (MP3, mono, 192 kbps or higher): All audiobook files must be submitted in MP3 format for maximum compatibility and optimized for streaming and downloading. Each file should be recorded in mono rather than stereo to keep file sizes manageable and to ensure a consistent sound across various listening devices. Furthermore, all files must be encoded at a minimum of 192 kbps to maintain a high level of clarity and fidelity in the voice recording, ensuring that listeners enjoy a crisp, clear experience. The Whisperboy Audiobooks QC Team will verify that the final product complies with these standards.
- Sample Rate (44.1 kHz): We require all audio files to be recorded at a 44.1 kHz sample rate. This rate is crucial because it ensures that we capture the full detail of the narrator’s voice without any loss of quality. It aligns with the industry standard for audio CDs, which means it offers a familiar, professional level of sound that listeners expect. If you record at a lower sample rate, it can result in audio distortion or muffled sound, which would detract from the listener’s experience. The Whisperboy Audiobooks QC Team will ensure all files maintain this consistency.
- Channels (Mono): Files should always be submitted in mono. By keeping the audio in a single channel, we ensure that the sound is evenly distributed through both ears, regardless of whether the listener is using headphones or speakers. This avoids the common problem of uneven sound that can occur in stereo recordings when played on certain devices. Additionally, keeping the file in mono helps with file compression and download times without compromising audio quality.
- File Length (No longer than 120 minutes): Each audio file should be limited to 120 minutes or less. This rule prevents excessively large files, which can slow down upload/download times or cause issues with playback. In cases where chapters are particularly long, break them into two or more parts. This approach also helps improve navigation for the listener, allowing them to easily pick up where they left off. The Whisperboy Audiobooks QC Team will review file lengths to ensure compliance.
2. Sound Quality
- Noise Floor (Below -60 dB): All audiobook recordings must have a noise floor below -60 dB. This means that when the narrator is not speaking, the background noise should be minimal and barely noticeable, ensuring a distraction-free experience. Achieving this requires recording in a controlled environment, such as a sound-treated booth or room. Any noticeable hums, computer fan noise, or external interruptions must be addressed before final submission. If necessary, noise-reduction techniques can be applied during post-production, but these should be used sparingly to avoid distorting the voice. The Whisperboy Audiobooks QC Team will ensure that noise levels are kept within the required range.
- Peak Levels (No higher than -3 dB): The loudest parts of the recording, or peak levels, should not exceed -3 dB. Exceeding this limit can result in audio clipping, leading to unpleasant distortions that detract from the professionalism of the audiobook. It’s essential to monitor recording levels throughout the session to ensure that no part of the file reaches this peak level. If you notice excessive peaks, use audio compression during post-production to smooth them out while retaining a natural dynamic range. The Whisperboy Audiobooks QC Team will closely check for any clipping or distortion during the review process.
- RMS Levels (Between -18 dB and -23 dB): RMS levels are the average loudness of the recording, and they should be maintained between -18 dB and -23 dB to ensure consistent audio output. This range is critical for making sure the audiobook is neither too loud nor too quiet. By achieving this balance, we ensure that listeners can comfortably hear the narration without constantly adjusting the volume. When editing, be sure to normalize and equalize the audio levels to stay within this range across the entire project. The Whisperboy Audiobooks QC Team will ensure that all files meet the RMS level requirements before submission.
- No Artifacts: To maintain Whisperboy’s high standard of audiobook production, all files must be free of artifacts such as sibilance (harsh “s” sounds), plosives (popping “p” and “b” sounds), or unwanted mouth clicks. These distractions can reduce the overall quality of the audiobook and frustrate listeners. Use a pop filter when recording and ensure the narrator maintains an appropriate distance from the microphone. In post-production, apply light de-essing and other corrective measures to minimize sibilance and any residual clicks. The Whisperboy Audiobooks QC Team will listen for any artifacts during quality checks and flag issues that need correction.
3. File Structure
- Separate Files for Each Chapter or Section: Each audiobook chapter or section must be uploaded as an individual file. This allows for easy navigation and improves the user experience by aligning the audio with the book’s natural divisions. Proper file labeling (e.g., “Chapter 01 – Title.mp3”) is required to ensure seamless organization and distribution. Please avoid combining multiple chapters into a single file, as this can create unnecessary confusion for listeners. The Whisperboy Audiobooks QC Team will inspect file structure and labeling to confirm everything is in order.
- Room Tone at the Beginning and End of Each File: Ensure that 0.5 to 1 second of room tone (silence captured in the recording space) is present at the beginning of each file and 1 to 5 seconds at the end. Room tone provides a smooth transition between chapters and ensures there are no abrupt cuts in the audio. This consistency contributes to a professional listening experience, so be mindful during recording to capture room tone effectively without any noticeable noises or distractions. The Whisperboy Audiobooks QC Team will ensure room tone is appropriately handled in each file.
- Opening and Closing Credits:
- Opening credits must include the title of the book, the author’s name, and the narrator’s name. This formal introduction sets a professional tone for the audiobook and is required for all files submitted through Audible and other platforms.
- Closing credits should reiterate the title of the book and the author’s name. In some cases, the narrator may choose to include a brief acknowledgment or thank you message, though this should remain professional and concise. These credits help listeners confirm the audiobook details and provide closure to the listening experience. The Whisperboy Audiobooks QC Team will review the credits for accuracy and consistency.
4. Metadata and Additional Requirements
- Retail Sample (1-5 Minutes Long): For every audiobook, a 1-5 minute retail sample must be provided. This sample is critical for promoting the book on platforms such as Audible, as it serves as a preview for potential buyers. The sample should ideally include a passage that represents the tone and quality of the book, offering listeners an enticing glimpse into the content. Select a section that highlights the narrator’s skill and the book’s engaging narrative without revealing any spoilers. The Whisperboy Audiobooks QC Team will confirm that the sample is appropriate for retail distribution.
- Cover Art (JPG or PNG, 2400×2400 pixels): High-quality cover art is mandatory and must meet the standard size of 2400×2400 pixels. The image should be submitted in JPG or PNG format and designed to attract potential listeners, providing a visual representation that complements the audiobook’s content. Keep in mind that the cover art is often the first impression a listener gets, so it should be eye-catching and professionally designed. The image must not contain URLs, promotional offers, or references to physical products (e.g., “includes free CD”). The Whisperboy Audiobooks QC Team will verify that the cover art meets all platform requirements.
Other Best Practices:
- Consistency in Volume and Performance: It is vital that each audiobook maintains consistent volume levels and a steady performance style from start to finish. Variations in volume or narration style can disrupt the listener’s immersion and negatively impact their experience. Make sure the narrator sustains an even tone and pace, avoiding any dramatic shifts unless dictated by the content. The Whisperboy Audiobooks QC Team will evaluate consistency across the audiobook.
- Pacing: Proper pacing ensures that listeners can follow the story without difficulty. If the narrator speaks too fast, listeners might miss important details. Conversely, speaking too slowly can cause the listener to lose interest. Encourage narrators to maintain a natural pace, allowing pauses where necessary to emphasize key moments and give listeners time to absorb the information. The Whisperboy Audiobooks QC Team will check that pacing is appropriate for the content.
- Editing: Every audiobook must undergo thorough editing to eliminate mistakes, inconsistencies, and distractions such as breaths, background noise, or vocal errors. Editing ensures a polished final product. Using professional editing software, review each file multiple times to guarantee that the narration flows smoothly and no errors remain. The Whisperboy Audiobooks QC Team will provide feedback if any further editing is required before final submission.
By following these guidelines, we ensure that Whisperboy audiobooks are not only compliant with industry standards but also deliver a high-quality experience that listeners will appreciate and remember. Our goal is to provide seamless, professional audiobooks that elevate the content and create lasting value for our customers.
Thank you for your continued dedication to maintaining the highest standards at Whisperboy. Let’s keep creating exceptional audio experiences that exceed expectations!
Please send your suggested amendments to Miss Lynda Hayes, our Head of Quality Control Department, at Lynda.hayes@whisperboy.com.
Content Quality Control Team
Whisperboy.com