A Guide To Understanding Sensitivity of Microphone

Microphone sensitivity holds a crucial position in the captivating realm of audio recording and broadcasting. It exerts its influence on a microphone’s prowess to capture delicate sounds and nuanced details, thus serving as a vital factor for both seasoned audio engineers and passionate enthusiasts. 

In this captivating article, we embark on an exploration of the intricate universe of microphone sensitivity, shedding light on its technical aspects, its impact on audio quality, and the key factors to ponder when selecting the perfect microphone to meet your needs. 

Join us on this captivating journey as we unravel the mysteries encompassing this essential microphone characteristic.

What Is Microphone Sensitivity?

Microphone sensitivity, often referred to as mic sensitivity or microphone output level, is a crucial technical parameter that quantifies a microphone’s responsiveness to sound waves. It is defined as the microphone’s output voltage or signal strength in response to a given sound pressure level (SPL). 

In simpler terms, microphone sensitivity expresses how loud or quiet a microphone can pick up sound. A high-sensitivity microphone produces a stronger electrical signal for a given sound level, making it suitable for capturing soft-spoken or distant sounds. Conversely, a low-sensitivity microphone generates a weaker signal and is better suited for high-SPL environments or close-mic applications. Understanding microphone sensitivity is essential for achieving optimal audio quality in various recording and broadcasting scenarios.

How Microphone Sensitivity is Measured?

Typically measured in millivolts per Pascal (mV/Pa) or decibels re 1 volt per Pascal (dBV/Pa), microphone sensitivity indicates how effectively a microphone converts acoustic energy (sound pressure variations) into electrical signals.

The measurement process involves the following steps

• Reference Sound Source: A calibrated sound source with a known sound pressure level (SPL) is used. This source produces a stable and consistent acoustic signal, typically a pure sine wave or pink noise, at a specific SPL level.
• Microphone Placement: The microphone under test is placed at a specified distance from the sound source. This distance is often set at one meter (1 m) or another defined value.
• Calibration: The microphone is calibrated using a reference microphone (known for its accuracy) to establish a baseline. This calibration accounts for any variations or irregularities in the microphone’s response.
• Sound Pressure Level (SPL) Measurement: The reference sound source emits a controlled sound signal, which reaches the microphone. The microphone converts this sound into an electrical signal.
• Voltage Output Measurement: The electrical output signal from the microphone is measured in volts (V) or millivolts (mV). This voltage output corresponds to the sound pressure level (SPL) generated by the reference sound source.
• Calculation: Microphone sensitivity is calculated based on the ratio between the measured voltage output and the known SPL of the reference sound source. It is typically expressed in mV/Pa or dBV/Pa.

Types of Microphone Sensitivity

Microphone sensitivity refers to how efficiently a microphone converts acoustic sound waves into electrical signals. There are several types of microphone sensitivity, each designed for specific applications:

• High Sensitivity Microphones: These microphones are designed to capture even the faintest sounds with precision. They are commonly used in studio recording, capturing delicate acoustic instruments, and for highly detailed audio capture.
• Low Sensitivity Microphones: These microphones are less sensitive and are ideal for high-volume sound sources or environments where loud sounds need to be captured without distortion. They are commonly used in live sound reinforcement, rock concerts, and recording of loud instruments like drums.
• Standard Sensitivity Microphones: These microphones offer a balanced sensitivity level suitable for a wide range of applications. They are versatile and can handle various sound pressure levels, making them popular choices for general-purpose microphones.
• Lavalier Microphones: These miniature microphones are often used in broadcasting and presentations. They have moderate sensitivity and are designed to be discreetly clipped onto clothing. They are well-suited for capturing spoken word and interviews.
• Shotgun Microphones: Shotgun microphones are highly directional and have moderate to high sensitivity. They are commonly used in film and video production to capture sound from a specific direction while rejecting off-axis noise.
• Boundary Microphones: Boundary or “PZM” (Pressure Zone Microphone) microphones are typically low sensitivity microphones designed to be placed on surfaces like tables or walls. They are used in conference rooms, boardrooms, and for capturing stage performances.
• Ribbon Microphones: Ribbon microphones have a unique sensitivity characteristic. They are known for their warm and vintage sound quality. They can handle high SPL but are generally less sensitive compared to other types.
• Dynamic Microphones: Dynamic microphones have moderate sensitivity and are robust and versatile. They are often used for live sound reinforcement, instrument amplification, and vocal applications.
• Condenser Microphones: Condenser microphones come in various sensitivity levels. They are known for their high sensitivity and accuracy, making them suitable for studio recording, vocals, and capturing fine acoustic details.
• Measurement Microphones: These microphones are designed for precision sound measurement applications. They often have a very flat sensitivity response to accurately capture and analyze sound for scientific or engineering purposes.

Why Is Microphone Sensitivity Important?

Microphone sensitivity is a critical parameter that directly impacts the quality and usability of audio recordings, making it an essential consideration when choosing the right microphone for any given application.

• Sound Capture Precision: Microphone sensitivity determines the microphone’s ability to capture subtle sounds and details, which is crucial for recording high-quality audio.
• Low Noise Floor: Higher microphone sensitivity reduces the need to amplify the audio signal during recording or broadcasting, minimizing the introduction of unwanted noise.
• Versatility: Different recording scenarios require different sensitivity levels. Having the right microphone sensitivity ensures optimal audio capture in various settings.
• Dynamic Range: Microphone sensitivity contributes to the microphone’s dynamic range, allowing it to handle both soft and loud sounds without distortion.
• Reduced Gain Requirements: Highly sensitive microphones require less additional gain from preamps or mixers, reducing the risk of introducing noise or feedback.
• Clarity in Quiet Environments: In quiet environments, sensitive microphones can capture faint sounds, making them suitable for ASMR recording, wildlife recording, and capturing delicate instruments.
• Noise Rejection: Lower sensitivity microphones are often used in noisy environments, helping to reject background noise and focus on the intended sound source.
• Sound Reinforcement: In live sound, microphones with varying sensitivities are used to amplify different sound sources accurately, such as vocals or instruments.
• Recording Detail: Sensitivity affects a microphone’s ability to reproduce fine details in sound, making it essential for critical audio recording applications.
• Sound Quality: Proper sensitivity selection contributes to overall sound quality, ensuring that audio recordings are faithful to the original source.
• Feedback Control: Microphone sensitivity can influence feedback issues in live sound situations. Choosing the right sensitivity helps prevent feedback and maintain clear sound.
• Compatibility: Matching microphone sensitivity to the intended application and equipment ensures seamless integration and optimal audio results.
• Energy Efficiency: Microphone sensitivity can affect power consumption in wireless microphones, impacting battery life and performance.
• Audio Engineering: Understanding microphone sensitivity is crucial for audio engineers and content creators to select the right microphone for a particular recording or broadcasting task.

Factors Influencing Microphone Sensitivity

Several factors influence microphone sensitivity, affecting how a microphone captures sound. These include:

• Microphone Type: Different microphone types (condenser, dynamic, ribbon) have varying sensitivity levels. Condenser microphones are typically more sensitive than dynamic microphones.
• Diaphragm Size: Larger diaphragms tend to be more sensitive and capture a broader range of frequencies compared to smaller diaphragms.
• Polar Pattern: The microphone’s polar pattern affects its sensitivity to sound from different directions. Omnidirectional microphones are equally sensitive in all directions, while directional microphones focus on specific sources.
• Diaphragm Material: The material used for the microphone diaphragm can impact sensitivity. Some materials are more responsive to sound vibrations than others.
• Preamp Gain: The sensitivity can be adjusted by adjusting the preamp gain on an audio interface or mixer. Increasing the gain amplifies the microphone’s output, effectively making it more sensitive.
• Impedance Matching: Matching the microphone’s impedance to the input impedance of the recording equipment can affect sensitivity. Mismatches can lead to reduced sensitivity.
• Acoustic Environment: The surrounding acoustic environment, including background noise and reflections, can influence microphone sensitivity. Noisy environments may require less sensitivity to avoid picking up unwanted sounds.
• Wind Protection: The use of windscreens or pop filters can affect sensitivity, particularly in outdoor or windy conditions.
• Distance From Sound Source: Microphone sensitivity can vary depending on the distance from the sound source. The proximity effect may increase sensitivity at close distances.
• Temperature and Humidity: Extreme temperature and humidity conditions can affect microphone sensitivity and performance.
• Signal Chain: The entire signal chain, from the microphone to the recording device, can impact sensitivity. The quality of cables, connectors, and preamps all play a role.
• Manufacturer Specifications: Manufacturers provide sensitivity ratings for their microphones. These specifications offer insights into a microphone’s sensitivity level.

How To Choose The Right Microphone Based on Sensitivity?

Choosing the right microphone based on sensitivity requires careful consideration of your specific recording needs. Here are some steps to help you make an informed decision:

• Identify Your Recording Environment: Determine where you’ll be recording. Is it a controlled studio environment, a live stage, or an outdoor location? The ambient noise and acoustic characteristics of the environment will impact your choice.
• Consider Sound Source: Understand the sound source you’ll be recording. Is it a loud instrument, a delicate acoustic performance, or vocals? Different sources have varying audio levels and tonal qualities.
• Microphone Type: Choose the microphone type that suits your application. Condenser microphones are generally more sensitive and capture subtle nuances, making them ideal for studio vocals and acoustic instruments. Dynamic microphones are less sensitive and handle high sound pressure levels, making them suitable for live sound and amplifying loud sources.
• Polar Pattern: Select the microphone with an appropriate polar pattern (omnidirectional, cardioid, figure-eight, etc.). The polar pattern determines how the microphone responds to sound from different directions. For isolating a single source, a directional pattern like cardioid may be preferable.
• Consider Microphone Specifications: Review the microphone’s specifications, including its sensitivity rating in decibels (dB). Higher sensitivity ratings indicate greater sensitivity to sound. Compare sensitivity ratings among different microphones to find the one that matches your requirements.
• Budget: Determine your budget for a microphone. Sensitivity often correlates with price. High-end condenser microphones with superior sensitivity may be costlier than dynamic alternatives.
• Test and Listen: Whenever possible, test microphones in your intended recording environment. Listen to how they capture sound and whether they deliver the desired results. Pay attention to noise levels and distortion.
• Accessories: Consider necessary accessories like shock mounts, pop filters, and windshields. These can affect sensitivity and overall microphone performance.
• Impedance Matching: Ensure that the microphone’s output impedance matches your recording equipment’s input impedance. Mismatches can lead to reduced sensitivity and audio quality.
• Room Acoustics: If you’re recording in a less-than-ideal acoustic environment, you may want to prioritize microphones with good off-axis rejection to minimize room noise.
• Dynamic Range: Consider the dynamic range of the microphone, which is the difference between the loudest and quietest sounds it can capture without distortion. A wider dynamic range can be beneficial in capturing both subtle nuances and loud transients.

Microphone Sensitivity Myths and Misconceptions

There are several myths and misconceptions surrounding microphone sensitivity. Let’s debunk some of the most common ones:

• Higher Sensitivity is Always Better: This is not necessarily true. While high-sensitivity microphones can capture subtle details, they are also more prone to picking up background noise and handling noise. The best sensitivity level depends on the specific recording situation.

• Sensitivity Determines Quality: A microphone’s sensitivity rating is just one factor that affects audio quality. Other factors like diaphragm size, design, and frequency response play crucial roles. A high-sensitivity microphone won’t guarantee excellent audio quality if other aspects are lacking.

• Sensitivity is Standardized: Sensitivity ratings can vary between manufacturers and even between different models from the same manufacturer. It’s essential to compare sensitivity ratings within the context of a specific microphone’s specifications.

• Dynamic Microphones Lack Sensitivity: While dynamic microphones are generally less sensitive than condenser microphones, this doesn’t mean they lack quality or applications. Dynamic mics excel in high sound pressure level environments and often provide excellent rejection of background noise.

• Sensitivity and Loudness Are the Same: Sensitivity measures a microphone’s output level for a given input. It doesn’t necessarily relate to how loud a microphone can capture sound. Microphones can handle loud sources without distortion, even if they have lower sensitivity ratings.

• Sensitivity is Unchangeable: Sensitivity can be influenced by various factors, including the microphone’s impedance, preamp settings, and distance from the sound source. Understanding these variables allows you to adjust sensitivity to your needs.

• More Expensive Means More Sensitive: While high-end microphones often have superior sensitivity, there are affordable microphones with excellent sensitivity for specific applications. Expensive microphones may offer additional features but not always better sensitivity.

• Sensitivity Affects Only Volume: Sensitivity impacts a microphone’s ability to capture quiet sounds, but it also plays a role in the microphone’s dynamic range, transient response, and overall tonal characteristics.

• Sensitivity is a One-Size-Fits-All Metric: The right sensitivity level depends on the application. Studio vocal recording, field recording, live sound reinforcement, and instrument miking all have unique sensitivity requirements.

• You Can’t Have Both Sensitivity and Durability: There are rugged microphones designed for demanding applications that also offer excellent sensitivity. The choice between sensitivity and durability depends on the specific microphone’s design and purpose.

How to Use Microphone Sensitivity Effectively?

Using microphone sensitivity effectively is crucial for capturing high-quality audio in various recording and sound reinforcement scenarios. Here’s how to make the most of microphone sensitivity:

• Select The Right Microphone: The first step is choosing a microphone with the appropriate sensitivity for your application. Consider factors like the sound source’s volume, the acoustic environment, and the desired level of detail in your recordings. Dynamic microphones are less sensitive and work well for high sound pressure level (SPL) sources, while condenser microphones are more sensitive and suitable for capturing nuances in quieter sources.
• Proper Placement: Mic placement is essential for optimizing sensitivity. Experiment with the microphone’s distance and angle relative to the sound source. Closer placement generally captures more detail and sensitivity. However, too close can lead to distortion or plosives, so finding the right balance is crucial.
• Gain Control: Adjust the microphone’s gain or input level on your audio interface or mixer. Higher sensitivity microphones may require less gain, while lower sensitivity ones may need more amplification. Avoid excessive gain, which can introduce noise and distortion.
• Room Acoustics: Be mindful of the acoustic environment. Use acoustic treatment or isolation techniques to reduce unwanted noise and reflections. A well-treated room enhances sensitivity by minimizing interference.
• Monitor Levels: Use headphones or studio monitors to monitor audio levels in real-time. Ensure that sensitivity adjustments result in clean and undistorted audio.
• Wind and Pop Protection: For sensitive microphones used in vocal recording, invest in pop filters and windshields to reduce plosives and wind noise that can affect sensitivity.
• Mic Preamp Quality: Quality microphone preamps can significantly impact sensitivity. Investing in a good preamp can help maintain signal integrity and maximize sensitivity.
• Match Microphone to Source: Select a microphone that complements the sound source. Different microphones have various frequency responses and tonal characteristics. The right match can enhance sensitivity and capture the desired sonic qualities.
• Monitor and Adjust: Continuously monitor recordings and make adjustments as needed. Pay attention to sensitivity levels during live sound reinforcement to ensure consistent and clear audio.
• Use a Shock Mount: A shock mount can isolate the microphone from vibrations and handling noise, preserving sensitivity during recording.
• Practice and Experiment: Sensitivity is a nuanced aspect of audio recording and reinforcement. Practice and experimentation will help you find the optimal settings and techniques for different situations.
• Post-Processing: If necessary, utilize post-processing techniques like equalization and compression to fine-tune audio captured with different microphone sensitivities.

Sensitivity of Microphone – FAQs

Conclusion

In summary, the sensitivity of a microphone plays a crucial role in capturing accurate audio, making it an essential factor for anyone working with microphones. Whether you’re a musician, podcaster, broadcaster, or sound engineer, mastering microphone sensitivity can greatly enhance the quality of your recordings. By carefully selecting the right microphone, implementing best practices, and taking other important factors into account, you can ensure that your audio projects sound exceptional, captivating your audience.