Concepts Explained

All of underwater acoustics is really a single question: a sound starts out at some loudness, weakens as it travels, and competes with background noise — can it still be heard? That balance is the sonar equation, and every panel in MuirWave is one term of it.

MuirWave computes each term from the real ocean at your pin. The rest of this page explains the two that do the heavy lifting: transmission loss (how the sea bends and weakens sound) and the sound-speed profile (why it bends the way it does).

Sound doesn't travel in straight lines underwater. Its speed changes with depth — warmer, shallower water carries sound faster; cold deep water slower; then pressure speeds it up again very deep. Sound rays always bend towards slower water, so this profile shapes where sound goes.

MuirWave builds this profile at your pin from ocean climatology (or live data, with MuirWave Live). It's the single most important input — change the profile and the whole prediction changes. The Water Column panel shows it for any spot.

Drop a pin anywhere in the ocean and MuirWave always has a profile — it ships with global climatology built in, so it works offline, worldwide, with no subscription. MuirWave Live layers real-time ocean data and high-resolution operating areas on top. The app uses the best source available and tells you which one on the SSP chip at the top of the Acoustics screen.

Models are the best guess available before you sail. Once you're on station with a bathythermograph or a live noise display, you have something better — and MuirWave treats it that way.

Enter a measured layer depth or measured noise points and they outrank every model tier — live feed included — for as long as you keep them switched on. The model keeps running underneath (live data keeps fetching, the comparison curves stay on the plots), so reverting never lands you on stale data, and the gap between model and measurement stays visible: that disagreement is field intelligence, not an error to hide.

Transmission loss (TL) is simply how much a sound has weakened by the time it reaches a given point — bigger TL means quieter. Because rays bend (§02), sound doesn't fade smoothly: it focuses in some places and thins out in others.

Put the loudness, the loss and the noise together and you get how detectable a source is at each point. MuirWave can paint this across the map as a field — a bird's-eye view of where a source would and wouldn't be heard.

On the Ray Path plot you can switch what's drawn: RAYS shows the ray paths, FIELD shows the continuous detection/loss field, and BOTH overlays them. The structure of the field comes from transmission loss; its overall level comes from the source and receiver you set.

For assessment work, the question flips: instead of "can I hear it?", it's "how far out could this sound affect an animal?" Regulators define thresholds — sound levels above which injury or a behavioural response is expected — that differ by species hearing group and by whether the sound is impulsive or continuous.

The globe's base land and sea follow the selected UTC date and time. Turning the camera does not move geographic sunlight. NOW keeps the light advancing with the existing minute refresh.

Day and night styling fades away as you zoom into the flat chart. Scientific layer colours and legends keep their meaning throughout; decorative lighting does not change a propagation prediction.

Use the browser console in portrait on phones and in landscape on tablets and larger screens. Tablet workspaces need at least 768 CSS pixels of width; desktop windows need at least 960 CSS pixels and must be at least as wide as they are tall. A rotate or widen message pauses access when the workspace does not fit.

Your scenario, selected chart reading and controls stay in place. Rotate or widen the window to continue where you left off. Opening the keyboard does not change the orientation requirement. After rotating back, tap a field to resume typing; touch keyboards do not reopen automatically. A narrow tablet split view still needs a wider landscape workspace. Sign-in and account recovery remain available from the message.

In Water Column, touch or hover over the plot to read depth, temperature, salinity and sound speed. The reading stays above the plot after you move away. In Ambient Noise, the frequency reading stays below the Wenz chart. Focus either chart and use arrow keys, Home or End to inspect with a keyboard.

Changing display units retains the selected depth. A changed profile clears its old reading. Wenz shows the four analytic terms and their spectral-density total separately from measured or solved noise; missing shipping data leaves the analytic total unavailable. Inspection reads the displayed data and does not run a prediction.

The web console uses an approximate GB7 intensity model. Its prediction, map, 3D field and exact cursor share the same propagation policy and supplied environment. FULL and DIRECT change the displayed extent; they do not change the physical horizon or integration step.

Phase interference and a complete arrival census are not modelled. Map cells and their interpolation approximate sampled intensities. Pending calculations and unsupported paths remain unavailable. A 3D source-depth preview has its own field; Reset returns to the committed scenario.

Open RADAR MAP in the forecast field tray to compare the smoothed one-way propagation factor with a standard atmosphere. The map uses a local aircraft antenna height from 50 to 10,000 feet. Its target height is independent; changing it reads the retained field. The other radar panels keep their own platform settings.

Every direction uses the same source atmospheric profile. Land and terrain are unmodelled, and the smooth-sea model includes editable profile assumptions. Colours show stronger or weaker propagation than the standard reference; they do not show detection reach or recommend an altitude. Ranges within ±3 dB have no wash. Missing cells and unsupported polar or globe-edge footprints stay masked.