The ornamental design for a white noisemachine, as shown and described.
FIG. 1 is a perspective view of a white noise machine showing my new design;
FIG. 2 is another perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is a bottom plan view thereof; and,
FIG. 9 is an enlarged view of portion 9 shown in FIG. 1.
The dot-dash broken lines seen in FIGS. 1 and 9 are the bounds of the enlarged view, while all other broken lines are included for the purpose of illustrating portions of the white noise machine; the broken lines form no part of the claimed design.