What is an RTA used for in live sound?

An RTA shows the tonal balance of your sound system in real time. Engineers use it during system tuning with pink noise to identify frequency ranges that are too loud or too quiet. It is the standard tool for checking equalization, verifying coverage uniformity, and documenting system response before events.

What is the difference between an RTA and an FFT spectrum analyzer?

An RTA groups FFT bins into octave bands and displays them as bars, providing a smoothed view ideal for overall tonal assessment. An FFT analyzer shows individual frequency bins, revealing fine detail. RTAs are better for EQ decisions; FFT analyzers are better for identifying narrow-band problems like feedback.

Which octave resolution should I use for system tuning?

Use 1/3 octave for initial system equalization and documentation, matching standard acoustic practice per IEC 61260-1. Switch to 1/6 octave for fine-tuning graphic EQ bands. Use 1/12 or 1/24 octave only when hunting specific narrow-band problems.

What is a spectrograph and when should I use it?

A spectrograph displays frequency versus time with color representing amplitude. Use it to see how sound changes over time, revealing intermittent feedback, HVAC cycling, traffic noise patterns, or audience impact on room acoustics. It shows patterns invisible in a standard RTA bar display.

Why does pink noise appear flat on an RTA?

Pink noise has equal energy per octave, which matches how RTAs sum energy within octave bands. White noise has equal energy per Hz, so it appears to rise 3 dB per octave on an RTA because higher octaves contain more Hz. Pink noise is the standard test signal for RTA-based system tuning.

Can I use an RTA to measure room acoustics?

An RTA shows the steady-state frequency response of the room plus sound system combined, useful for identifying room modes and coverage problems. However, for detailed acoustic parameters like RT60, clarity, and speech intelligibility, you need impulse response measurements per ISO 3382-1.

How does averaging affect RTA measurements?

Linear averaging sums multiple frames to stabilize the display, reducing noise but slowing response. Exponential averaging weights recent frames more heavily. Peak hold captures the maximum level per band over the measurement period. For system tuning, use 4-8 second exponential averaging with pink noise.

Is a phone RTA accurate enough for professional use?

Phone RTAs are accurate for relative measurements like comparing before/after EQ changes. For absolute SPL-per-band accuracy, you need a calibrated measurement microphone. SonaVyx supports importing calibration files to correct for your specific microphone frequency response.

What is an RTA used for in live sound?

An RTA shows the tonal balance of your sound system in real time. Engineers use it during system tuning with pink noise to identify frequency ranges that are too loud or too quiet. It is the standard tool for checking equalization, verifying coverage uniformity, and documenting system response before events.

What is the difference between an RTA and an FFT spectrum analyzer?

An RTA groups FFT bins into octave bands and displays them as bars, providing a smoothed view ideal for overall tonal assessment. An FFT analyzer shows individual frequency bins, revealing fine detail. RTAs are better for EQ decisions; FFT analyzers are better for identifying narrow-band problems like feedback.

Which octave resolution should I use for system tuning?

Use 1/3 octave for initial system equalization and documentation, matching standard acoustic practice per IEC 61260-1. Switch to 1/6 octave for fine-tuning graphic EQ bands. Use 1/12 or 1/24 octave only when hunting specific narrow-band problems.

What is a spectrograph and when should I use it?

A spectrograph displays frequency versus time with color representing amplitude. Use it to see how sound changes over time, revealing intermittent feedback, HVAC cycling, traffic noise patterns, or audience impact on room acoustics. It shows patterns invisible in a standard RTA bar display.

Why does pink noise appear flat on an RTA?

Pink noise has equal energy per octave, which matches how RTAs sum energy within octave bands. White noise has equal energy per Hz, so it appears to rise 3 dB per octave on an RTA because higher octaves contain more Hz. Pink noise is the standard test signal for RTA-based system tuning.

Can I use an RTA to measure room acoustics?

An RTA shows the steady-state frequency response of the room plus sound system combined, useful for identifying room modes and coverage problems. However, for detailed acoustic parameters like RT60, clarity, and speech intelligibility, you need impulse response measurements per ISO 3382-1.

How does averaging affect RTA measurements?

Linear averaging sums multiple frames to stabilize the display, reducing noise but slowing response. Exponential averaging weights recent frames more heavily. Peak hold captures the maximum level per band over the measurement period. For system tuning, use 4-8 second exponential averaging with pink noise.

Is a phone RTA accurate enough for professional use?

Phone RTAs are accurate for relative measurements like comparing before/after EQ changes. For absolute SPL-per-band accuracy, you need a calibrated measurement microphone. SonaVyx supports importing calibration files to correct for your specific microphone frequency response.

Real-Time Audio Analyzer (RTA)

A real-time audio analyzer (RTA) displays the frequency content of a sound signal as continuously updating octave band bars, providing an intuitive visual representation of tonal balance. SonaVyx delivers IEC 61260-1-compliant RTA with 1/1 to 1/24 octave resolution, spectrograph mode, and multi-trace overlay using Rust WASM processing at native speed in your browser.

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Open the real-time analyzer in your browser — free, no download needed.

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Technical Specifications

Parameter	Value	Standard
Display Mode	Bar graph + line + spectrograph	User selectable
Octave Bands	1/1, 1/3, 1/6, 1/12, 1/24	IEC 61260-1
Frequency Range	20 Hz - 20 kHz (31 bands at 1/3 oct)	IEC 61260-1 Table 1
Update Rate	20-60 fps (device dependent)	requestAnimationFrame
Weighting	A, C, Z (linear)	IEC 61672-1 Class 2
Averaging	Off / Linear / Exponential / Peak Hold	User selectable
Spectrograph History	5s, 10s, 30s, 60s	Scrolling time-frequency

How to Use the Real-Time Analyzer

Open RTA Mode

Navigate to the measurement workspace and select the RTA tab. SonaVyx requests microphone access and begins live audio capture at your device sample rate (typically 44.1 or 48 kHz).

Select Band Resolution

Choose 1/3 octave for standard acoustic measurements or 1/6 octave for more detail. Higher resolutions like 1/12 or 1/24 octave reveal narrow-band anomalies but require more screen space.

Apply Weighting

Select A-weighting for perceived loudness assessment, C-weighting for peak levels, or Z (linear) for flat system analysis. A-weighting is required for OSHA and ISO 9612 noise measurements.

Read the Display

Each bar represents the energy in that octave band. Taller bars mean more energy at that frequency. Compare against pink noise reference (flat across all bands) to assess system frequency balance.

Toggle Spectrograph

Switch to spectrograph view to see how frequency content changes over time. Color encodes amplitude: dark blue (quiet) through green and yellow to red (loud). This reveals intermittent problems invisible in the bar display.

Understanding Real-Time Audio Analysis

The real-time analyzer has been the primary tool for sound system equalization since the 1970s. Unlike an FFT analyzer that shows individual frequency bins, the RTA groups energy into standardized octave bands defined by IEC 61260-1. This produces a cleaner, more intuitive display where each bar corresponds to a perceptually meaningful frequency range. Engineers can immediately see if the bass is too heavy, the midrange is scooped, or the high frequencies are rolling off.

RTA in System Tuning Workflow

The standard approach to system equalization uses pink noise as the test signal because it has equal energy per octave band. When played through the PA and measured with an RTA, deviations from a flat response indicate room interaction, speaker frequency response issues, or EQ misadjustment. The engineer adjusts the system graphic or parametric equalizer until the RTA shows a flat or gently tilted response across all bands.

Spectrograph: Adding the Time Dimension

A conventional RTA shows only the current instant. The spectrograph extends this by plotting frequency on one axis, time on another, and using color to represent amplitude. This waterfall-style display reveals temporal patterns: the 120 Hz hum that appears every 30 seconds when the air conditioning compressor cycles, the feedback frequency that builds gradually before becoming audible, or the audience noise that shifts the room response during a show.

Limitations of RTA-Only Tuning

While the RTA is essential, it shows only magnitude. It cannot reveal phase problems, comb filtering from reflections, or coherence issues between measurement positions. Modern system tuning combines RTA measurements with transfer function analysis (which shows both magnitude and phase) and impulse response measurements (which show time-domain reflections). SonaVyx provides all three modes in a single unified workspace.

RTA Software Comparison

Feature	SonaVyx	Smaart v9	REW	OSM
Octave band bar display	Yes	Yes	Yes	Yes
Spectrograph view	Yes	Yes	Yes	No
1/24 octave resolution	Yes	Yes	Yes	No
Peak hold	Yes	Yes	Yes	Yes
Browser-based	Yes	No	No	No
Trace storage	10 traces	Unlimited	Unlimited	2
Price	Free	$898	Free	Free

Frequently Asked Questions

Related Tools & Resources

Spectrum Analyzer

FFT line spectrum with fine frequency resolution

Pink Noise Generator

Generate pink noise test signal for RTA measurements

Transfer Function

Dual-channel magnitude and phase analysis

Octave Band (Glossary)

Understanding octave and fractional octave bands

Standards References

IEC 61260-1:2014 — Octave-band and fractional-octave-band filters: Specifications
IEC 61672-1:2013 — Sound level meters: Specifications (A/C/Z frequency weighting)
ANSI S1.11-2014 — Specification for octave-band and fractional-octave-band analog and digital filters
AES-6id-2006 — AES information document for digital audio measurements: Noise bandwidth