A slow bass note and a note that rings out over everything around it are different problems. Before opening an analyzer, describe what the guitar is doing under your hands. The measurement is useful when it helps you investigate that observation, not when it gives you a more impressive way to describe it.
Software cannot decide whether a guitar is good. It can help you inspect frequency content, follow decay, and compare a recording made before a change with one made afterward. What matters is whether that information changes a decision.
What the Measurement Needs to Show
Start with clean recording, a readable spectrum, and a way to compare saved measurements. A spectrogram or waterfall adds time to the picture. That matters because a strong peak and a long decay are not the same thing. A frequency that hangs on after its neighbors have faded may be worth investigating if you also hear it dominating a passage.
Keep the input in mind. A bridge tap, a plucked string, and a swept excitation do not ask the instrument the same question. A microphone records sound at its position. An attached accelerometer records motion at its attachment point. Each gives a particular view, not a complete description of the guitar.
I would establish a repeatable routine before adding equipment. Keep the room, microphone position, recording level, and excitation consistent. That is repeatability, not necessarily calibration. Without it, you can spend time explaining differences that came from the test rather than the instrument.
Which Kind of Software Fits the Work?
These are different tools for different questions, not the results of a controlled comparison. A quick recording check, an acoustic measurement, and a custom research process need different levels of control. Choose around the work you actually need to do.
Audacity: Recording and a First Inspection
Audacity provides a straightforward place to record, trim, and inspect audio in spectrum or spectrogram views. Record open strings, individual notes, or a repeatable tap sequence. Keeping those files is useful when comparing instruments or returning to a guitar after setup work.
The limitation is the measurement procedure, not a reason to dismiss the recordings. An audio editor does not establish a calibrated guitar test for you. You still have to choose the input, control the recording conditions, and decide what the display can support. A casual recording is not a basis for precise absolute values.
Room EQ Wizard: A More Controlled Measurement Setup
Room EQ Wizard, or REW, approaches measurement from loudspeaker and room work. Sweep, impulse-response, frequency-response, and decay tools can be useful in instrument work too, provided the excitation and recording arrangement suit the question. Having a relevant plot available is only part of that arrangement.
There is more setup to understand: signal routing, levels, calibration, and the relationship between the source and microphone. A tidy graph will not tell you that the microphone moved. Nor will a room-oriented workflow automatically separate the guitar from its surroundings. Use the views that answer your question and leave the others alone.
With consistent support and a documented microphone position, REW is a candidate for repeatable shop comparisons. Its usefulness depends on the procedure built around it, not on the number of plots it can produce.
Sonic Visualiser: Looking Inside a Recorded Note
Sonic Visualiser is worth considering when an averaged spectrum hides what you hear. Time-frequency views let you look more closely at the attack, changing partials, beating, and decay of a recorded note. That can help locate the part of a troublesome note that needs closer listening.
You still need to record and organize comparable samples. Treat this as an inspection stage within the work, rather than assuming the application supplies the entire measurement process. Labelled source recordings remain important.
ARTA: A Technical Measurement Environment
ARTA offers spectrum, impulse-response, transfer-function, and distortion tools in a Windows-oriented measurement environment. Those tools can be relevant to instrument research when the interface, sensors, excitation, and procedure are chosen together. There is an important lifecycle limit: the developer reports that development ended in March 2024, ARTALABS closed in April 2024, and version 1.9.8 became freeware in December 2024. Treat it as legacy software, and check compatibility before building a new measurement routine around it.
The terminology and setup ask more of the user than a basic recording editor. I would approach it with a defined measurement in mind. More technical controls do not make it easier to decide what resonance data means, and they are not a substitute for learning the limits of the test.
MATLAB or Python: When the Question Needs Custom Analysis
Custom analysis becomes useful when the standard displays cannot do the job. Possible reasons include processing repeated recordings, comparing a collection of instruments, calculating a particular decay measure, or handling impact-hammer and accelerometer data in a consistent way.
That freedom comes with responsibility for the calculations and their interpretation. A script can process a poor measurement just as readily as a good one. Get the recording routine stable, check the method against known examples, and only then automate the repeated work.
Start With the Question
Choosing between two guitars may need nothing more elaborate than comparable recordings of the same passage. Spectrum and decay views can support the listening. They do not, on their own, explain every difference in immediacy or sustain that the player notices.
Investigating top thickness, brace changes, or bridge mass calls for tighter control. Record at known stages and keep notes about the physical changes. Several repeatable measurements are more informative than one attractive graph. A more technical application earns its place when it supplies control the comparison actually needs.
A question about mode shapes needs spatial information. A microphone spectrum can help locate resonances, but it does not map how the body moves. Chladni patterns, measurements at multiple locations, scanning methods, or controlled accelerometer work address different parts of that problem. The software remains one part of the test.
Make the Recordings Comparable
Choose one excitation method and stay with it. For a quick comparison, mark the bridge tap location and aim for consistent contact and force. An instrumented impact hammer can provide information about the input, but still needs careful use. For played notes, record several takes so one unusual attack does not become the result.
Support the guitar the same way for each measurement. Holding it against a player, resting it on a bench, and suspending it are different conditions. Decide which condition matters to the question instead of treating one arrangement as a universal reference.
Mark microphone distance and angle. Do not move it until the graph looks more convincing. A second position can be useful, but label it as another view. Keep the audio as well as the screenshots, with the date, strings, instrument condition, humidity, and test method.
Return to playing before deciding that a change helped. A bridge replacement might change a measured balance of partials without making the instrument more useful to its player. An accurate observation and a worthwhile improvement are two separate judgments.
What the Graph Does Not Settle
A frequency peak is not a verdict. Top, back, air cavity, bridge, strings, and neck interact, while the player and room affect what gets recorded. A peak that causes trouble in one guitar may sit comfortably within another guitar's response. Look at its surroundings and decay, then listen.
Unmatched recordings are another common trap. A changed attack, moved microphone, fresh strings, or different humidity can give you a difference that is real but unrelated to the work you intended to assess. Increasing display resolution does not remove those confounding changes.
Repeatability also needs relevance. A test can give the same answer each time without addressing the player's complaint. Keep the listening question beside the measurement and ask whether the result helps explain it.
Begin with a program you can use consistently. Save a baseline, repeat the test enough to understand normal variation, and add complexity only when you can name the question it will answer. Analysis should support judgment, not take its place.