How do I "say . . . using" in Javascript for Automation? In Applescript, I can specify the voice the system uses to speak text as follows:

say "Hello" using "Alex"


In Javascript, I can do something similar:

var ScriptEditor = Application("Script Editor");
ScriptEditor.includeStandardAdditions = true;

ScriptEditor.say("Hello!")


But I don't know how to specify the specific voice; I always have to use the system. Is there a way to specify the using parameter, or another version of say that allows the code to specify the voice?
Apple's documentation describes how to call commands which have both direct parameters (the text) and named parameters (the using). In this case, you would do this:

var ScriptEditor = Application("Script Editor");
ScriptEditor.includeStandardAdditions = true;

ScriptEditor.say("Hello", {using: "Alex"})