improve: rework `VoiceModel` #2848

Job	Run time
actionlint	19s
build-and-test-java-api (windows-latest)	7m 26s
build-and-test-python-api (windows-latest)	6m 48s
build-and-test-java-api (macos-latest)	3m 4s
build-unix-cpp-example (macos-latest, osx-x64-cpu-cpp-shared)	1m 30s
build-unix-cpp-example (ubuntu-latest, linux-x64-cpu-cpp-shared)	1m 37s
build-and-test-python-api (macos-latest)	3m 38s
build-and-test-java-api (ubuntu-latest)	2m 53s
build-and-test-python-api (ubuntu-latest)	3m 9s
build-windows-cpp-example	3m 20s
c-header	48s
rust-integration-test-strategy-matrix	1s
rust-unit-test	3m 13s
rust-lint	3m 26s
shellcheck	11s
validate-cargo-lock	21s
rust-integration-test (macos-12)	3m 39s
rust-integration-test (ubuntu-20.04)	1m 25s
	46m 48s

Provide feedback