A dominant seventh suspended fourth chord is composed using a root/1st, perfect 4th, perfect 5th and a minor 7th (or R/1-4-5-♭7) intervals played simultaneously. Generally written as C7sus4 or C7sus4, it is good practice to simply use an uppercase C followed by a super scripted 7sus4 to represent it in writing (ie: C7sus4).
The dominant seventh suspended fourth chord is enharmonic to a minor seventh suspended fourth chord as there is no 3rd degree present in either, and both have a minor 7th interval. Like the suspended fourth chord, its quality (ie: minor, dominant) is implied by its resolution (if any) however in this instance, resolution is either minor or dominant, not major (this is due to the minor 7th being present in both). As an example, if you were to play a D7sus4 followed by a D7, the implied quality would be dominant because the perfect 4th (suspended 4th) is resolving to a major 3rd one half step lower, while the minor 7th remains. Alternatively, if you were to play the same D7sus4 chord but this time follow it with a Dmi7, its implied quality would be minor because the perfect 4th is resolving to a minor 3rd one whole step lower, and again the minor 7th remains.
It is not necessary to resolve the dominant seventh suspended fourth or the minor seventh suspended fourth chords, it is merely a tonal tool we can use if required.
Dominant seventh suspended fourth chord profile
|Intervals||root/1st, perfect 4th, perfect 5th, minor 7th or R/1-4-5-♭7|
|Stability||Somewhat dissonant, unresolved|
|Common names (examples in C)||C7sus4, C7sus|
|C Dominant seventh suspended fourth chord voicing #2|