der Unterton
undertone
An implied, not directly stated meaning, intention, or emotional tone in an utterance or action.
In seiner Stimme war ein drohender Unterton zu hören.
There was a threatening undertone in his voice.

undertone
Loading your saved state.
undertone
An implied, not directly stated meaning, intention, or emotional tone in an utterance or action.
In seiner Stimme war ein drohender Unterton zu hören.
There was a threatening undertone in his voice.

The word consists of 'unter' (under) and 'Ton' (tone). This compound helps with both meanings: it is either an emotional tone that lies 'under' the words, or an acoustic tone that resonates 'under' a main tone.
Obwohl er lächelte, spürte ich einen kalten Unterton in seiner Begrüßung.
Although he smiled, I sensed a cold undertone in his greeting.
You can recognize the figurative meaning from words that describe communication (voice, criticism, words). You can recognize the literal, acoustic meaning from technical terms from music or physics (sound, frequency, analysis).
Ihre Frage hatte einen neugierigen Unterton.
Her question had a curious undertone.
In the figurative meaning, 'Unterton' (undertone) is often combined with adjectives that describe the emotion being implied, e.g. an 'ironischer' (ironic), 'kritischer' (critical), 'sarkastischer' (sarcastic), or 'freundlicher' (friendly) undertone.
Er bemerkte den ironischen Unterton in ihrer Stimme nicht.
He did not notice the ironic undertone in her voice.
To express how something is said, German often uses the fixed expression 'mit einem ... Unterton' (with a ... undertone).
Sie erzählte die Geschichte mit einem amüsierten Unterton.
She told the story with an amused undertone.
The acoustic meaning of 'Unterton' (undertone) is a technical term and is used almost exclusively in contexts such as music theory, acoustics, or physics.
In der Akustik beschäftigt man sich mit Obertönen und Untertönen.
In acoustics, people study overtones and undertones.
sound
'der Klang' and 'der Unterton' can both mean something that resonates in words and is not said directly. 'Klang' describes more the general impression of a word, name, or sentence. It can feel friendly, harsh, or official. 'Unterton' refers more specifically to a hidden attitude or feeling in an utterance, for example criticism, anger, or irony. The words can be confused because both talk about more than just the literal content. When it is about the general impression, 'Klang' fits better; when a hidden message or mood is meant, 'Unterton' fits better.

In seiner Frage lag ein kritischer Unterton.
There was a critical undertone in his question.
Der Klang ihrer Antwort war freundlich, obwohl sie kurz war.
The tone of her answer was friendly, even though it was brief.